Is Bin Laden dead or alive?

The marks of truck tyres were still visible in the soft earth of the tunnel floor that stretched, dark and silent, into the heart of the mountain. I was standing in a cave which until recently had been the hideout of an al Qaeda commander. Beyond the entrance to the cave, a narrow track littered with boulders led precipitously down from the mountain pass to the badlands of the tribal areas which straddle the southern Afghan border with Pakistan.

Operation Anaconda, the great set piece battle of the "war against terror", between al Qaeda and the coalition forces, had just drawn to its bloody close, in the valley of Shah-IKot below. It had claimed the lives of 12 American soldiers and several hundred al Qaeda fighters. As the first anniversary of 11 September approached I had come to Paktia province in Afghanistan, for BBC's Panorama programme, to assess who was winning the war and to find out how the hunt for Osama bin Laden was progressing.

I had already encountered a few surprises on the wind-swept dusty plain at Bagram where the coalition troops are based. The first was the grudging respect that al Qaeda had earned among the American military, at all levels.

"They were well supplied, well equipped, well trained," Lt Col Jasey Briley, the chief US military officer at Bagram told me. "They had solar panels, Gore-Tex clothing, some of the best waterproof equipment in the world."

"I have even more respect for the enemy now," admitted Major General "Buster" Hagenbeck, the overall US commander. "There was not a single occasion of any of them even attempting to surrender even when they knew death was imminent, eyeball to eyeball."

The military claimed that the three-week battle in Shah-I-Kot had resulted in the rout of al Qaeda but they were already concerned at what that would mean in the long term. "It's like stamping on a pool with your boot," admitted Briley, "you never know where those myriad drops of water will land and if they will flow together again."

One year on from the attacks on America the war against terror has become a long, drawn-out guerrillastyle operation waged both in Afghanistan and neighbouring Pakistan and far beyond. The US missed its best chance to capture or kill Osama bin Laden at the battle of Tora Bora last December, by relying on treacherous and corrupt Afghan proxies rather than risking a sizeable-US force on the ground to carry out the task. Al Qaeda was in disarray in January and February of this year, its forces scattered and on the run, its leader wounded in the American bombing of his cave complex at Tora Bora. He appeared gaunt and grey on a video as 2002 dawned but in the absence of a body, or signals from inside the al Qaeda camp that their leader was dead, intelligence agencies in Europe and the US have been forced to conclude he must be alive and still in the area.

There have been many reported sightings of the elusive Saudi renegade in the border area between Pakistan and Afghanistan. Sources close to al Qaeda have told me that not only is Bin Laden alive but he is in command and that al Qaeda is once again adjusting to changed circumstances, re-inventing itself the better to confront and wound its enemy, America.

In early spring an al Qaeda commander carried a personal message from Bin Laden to his fighters massing in the Shah-I-Kot valley in anticipation of Operation Anaconda. Some were to remain in Afghanistan to fight the Americans and others were to return to their home countries "and strike a blow against American and Jewish" interests. And so the warriors of the jihad returned, along snow- covered tracks to Pakistan and through Iran and Baluchistan to the Yemen, Egypt and North Africa and even further afield, back to their communities in European cities to plan and await their opportunity to strike.

In March a church was bombed in Islamabad killing five Americans and Pakistanis. Two more bombs in Pakistan killed 11 French naval workers and more local people. In Tunisia in April an al Qaeda fanatic loaded a truck with cylinders of gas and detonated it outside an ancient synagogue killing 18 German tourists in the holiday resort of Djerba. Bin Laden's "spokesman" appeared on a tape aired on al Jazeera television to claim responsibility and promise more attacks.

AL Qaeda had shown their intent and ability to strike on the shores of the Mediterranean at European targets. A foiled attempt to target British warships in the straits of Gibraltar in June reinforced the message that Tony Blair's staunch support for the war on terrorism had been noted in al Qaeda circles and would be acted on.

Intelligence agencies believe the seven attacks since 11 September which have succeeded in killing nearly two dozen westerners fit a new pattern of al Qaeda terror which is emerging. Bin Laden's aim has always been to create an umbrella organisation to provide inspiration, financing and logistical support for a number of militant islamic groups.

Al Qaeda's hallmark became the big set-piece terror attack, many years in the planning, which brought together dozens of highly trained and motivated individuals, many of whom passed through the Afghan training camps. The bombings of the US embassies, the attack on the USS Cole and the 11 September attacks on New York and Washington, all fitted the pattern. Now with the Afghan training camps destroyed, al Qaeda - which means "the base" - has no home territory to call its own and must find a new modus operandi. It is now acting through lone individuals and small ad hoc groups of fanatics with grievances who are coming together in many different countries to present a new and continual threat.

Richard Reid, the British shoe bomber, a loner who tried to blow up an American Airlines jet three months after 11 September, was the first manifestation of this new wave of al Qaeda terror. Kerim Chatty, the 29-year-old Swedish citizen who tried to smuggle a handgun aboard a Ryanair flight to Stansted, is thought to be one of the last. Every week European newspapers record the arrests of small groups of individuals - the latest, a Turkish man and his American girlfriend, believed to be plotting to kill American soldiers in Germany. All this suggests a new danger from radicals tied loosely to the old terror network and freelance extremists inspired to copycat acts.

America and its coalition partners have had only limited success in tracking down or killing key members of al Qaeda's hierarchy. Their biggest catch was undoubtedly Abu Zubaydah, seized in Pakistan in March. He was the organisation's number three and the man responsible for recruitment and for assigning individuals to the terror cells scattered in up to 60 different countries around the world. But Zubaydah was captured six months ago now and intelligence officers have ruefully concluded that no one can be certain that the leads he provided were real or just deliberate disinformation. Sources close to al Qaeda have let it be known that the fractured nature of the organisation means that no one individual has complete knowledge of plans in the pipeline.

Another key individual, Sheikh Ahmed Salim, wanted for his involvement in the 1998 East African bombings at US embassies, is also believed to have been apprehended in Karachi where he had been directing a small cell of Pakistani militants since fleeing Afghanistan in the wake of 11 September. What he has told investigators bears out the theory that al Qaeda operatives are becoming more self-sufficient, seeking new and fanatical recruits in a number of countries in order to create a wave effect of smaller scale terror attacks.

Still at large, however, are not only Bin Laden himself and his deputy and mentor, Dr Ayman al-Zowahiri, but also key members of al Qaeda's "middle management". Among them are two individuals who have successfully adopted the guise of globe-trotting businessmen while planning for the attacks on the twin towers and the Pentagon. Khalid Sheikh Mohammed, a veteran of an earlier unsuccessful attempt to blow up the World Trade Center, has now boasted to an Arab journalist from his hideout in Karachi that he created the blueprint of the 11 September multiple hijack plan. Mustafa Ahmed, the key financier who set up and secretly fed the bank accounts of the al Qaeda pilots and their henchmen during their stay in Florida, is also still at large.

Just as the terror network is mutating into something wider, more fractured and difficult to detect, so too the finances of the terror group show signs of being revived. The much- vaunted attempt by governments worldwide to crack down on al Qaeda's bank accounts and assets has stalled. There have been reports that gold, a favoured commodity of Bin Laden's, is filtering out of Afghanistan, via Pakistan and Dubai, to an old haunt - Khartoum, the capital of the Sudan. Al Qaeda had an extensive and wellorganised network of companies and farms in the Sudan in the early and mid-Nineties and some of that financial network is believed to still exist.

Intelligence agencies believe this movement of gold indicates that al Qaeda still has access to significant financial reserves and is able to generate revenue. It also shows that some of Bin Laden's fortune remains intact.

The debate over whether Bin Laden is dead or alive still rages, fuelled by the latest revelation from al Jazeera television in which his followers speak about him in the past tense. It suits both al Qaeda and America to have him still at the helm - al Qaeda can rally supporters around the charismatic figurehead and America can pursue the war on terror with the aim of eliminating the world's most wanted man.

Tomorrow the world will hold its breath for fear that al Qaeda will mark the anniversary of 9/11 with another attack - to prove it is still in business. But Bin Laden has always played a long and patient game and al Qaeda may wait to see what America will do in Iraq. Those close to his organisation suggest that he is hoping to increase his support in the Middle East and if America launches a war against Saddam Hussein it is then that al Qaeda will strike again. Rumours persist that a "dirty" bomb, a radiological device to scatter nuclear debris in a western city, is the goal that they are heading for.

The caves above the valley of Shah-I-Kot are empty but Paktia province is not secure and there is an ominous sense of unfinished business in these mountains where westerners are still unwelcome and locals are sympathetic to Islamic militants. There are persistent reports of a small band of al Qaeda warriors on horseback, led by Bin Laden, moving at night among the mountains - on the run but still a force to be reckoned with. The war against terror has moved beyond Afghanistan but it is not yet over. No one knows where al Qaeda will strike next and who they will kill.

? Jane Corbin's book The Base: In Search of al Qaeda, is published by Simon and Schuster.