Did Abramovich steal a £1.2 bn stake in oilfield?

Chelsea's surprise defeat in Rome on Tuesday night may have disappointed Roman Abramovich but it may not preoccupy him for long. He has a match of a quite different kind on his mind. Lawyers in London are expected to decide this week whether to pursue a case against him on behalf of investors who have made a startling allegation. Abramovich, they say, effectively stole their £1.2 billion oilfield. The Russian billionaire has strenuously denied the allegation and many will find it an outlandish proposition.

At 42, Abramovich is one of the world's richest men with a fortune estimated at £15 billion and although there have been dark murmurings about how he managed to rise from street trading in Moscow to controlling one of Russia's biggest oil concerns, no one has ever proved he acted improperly. Now a long-running argument over ownership of a fabulously rich Siberian oilfield is reaching its endgame here in London. Abramovich has just won an important round in this fiercely-fought legal battle in the High Court but the Evening Standard has learned an appeal is being discussed.

If it goes ahead, it would plunge the Chelsea owner back into a legal maelstrom that has swirled around him for more than three years. At its heart is a claim that he and his company, Millhouse Capital, swindled investors - including more than 4,000 British shareholders - in a deal over a Russian oilfield described by one expert as "the pearl of western Siberia".

The Priobskoye field sits on a vast bog and can be worked only in winter when the ground freezes. It is more than 1,500 miles from Moscow and is one of the most hostile places on earth but in its southern part, wells are producing 150,000 barrels of oil a day. Half of these riches were owned by a British-based company, Sibir Energy, but according to its chief executive, Henry Cameron, they were stolen in what he described in a letter to shareholders as "barefaced corporate robbery".

Cameron is an Aberdeen lawyer who was dealing with the Russians when the Soviet fishing fleets came to Scotland in the Eighties. He switched to oil and, backed by British investors, headed a company that became Sibir. Part of its holding was a licence to drill for oil in Priobskoye. Sibir, through another company called Yugraneft, joined forces with Abramovich's oil giant, Sibneft, to exploit the Priobskoye field.

In his office in Mayfair, Cameron revealed how a venture he believed could make his investors rich turned into one of the oil industry's most bitter disputes. He speaks coolly, with all the detail of a complicated case at his command. But there is no disguising his anger.

Last week Mr Justice Christopher Clarke concluded in the High Court that the English courts were not the right place to decide the allegations against Abramovich. The billionaire was neither resident nor domiciled here, he said, adding that the case was about "the conduct of Russians, in Russia under Russian law". He dismissed Yugraneft's claims and said they were "an abuse of process".

Cameron is unrepentant. His team of lawyers is looking at grounds for an appeal and a decision is likely within the next few days. It will be watched closely by British companies who deal with Russia.

Some may wonder why, after this High Court setback, Cameron would seek to carry on fighting. The reason, he says, is that he believes a wrong was committed and he wants justice.

In his ruling, Mr Justice Christopher Clarke noted the Cameron camp's contention that "what has happened is nothing less than fraud on a grand scale". Cameron says trouble started soon after his company, Sibir, and Abramovich's Sibneft agreed their deal to exploit the Priobskoye field.

At first, Cameron says, everything seemed to go well. Then Sibir started talks to buy into Moscow's huge oil refinery, the only one in the city and considered one of the Russian oil industry's great prizes. Also bidding for the Moscow refinery was Abramovich's Sibneft, which had long sought control of this strategic asset.

This is the point in the story at which personalities appear to play a part. Sibir's biggest shareholder is Chalva Tchigirinsky, a construction tycoon who counted the mayor of Moscow, Yuri Luzhkov, among his friends. The mayor controlled the oil refinery through the large stake held by the City of Moscow.

Mr Luzhkov was no friend of Abramovich. Luzhkov once noted the hundreds of millions of pounds Abramovich was sinking into Chelsea Football Club and said: "He is spitting on Russia." His words stung Abramovich. He has invested heavily in Russian football. Charities in the country, especially those for Jewish causes, have benefited greatly from his wealth. He judged Luzhkov's rebuke unwarranted and unfair. Injury was added to this insult, it seemed, when Luzhkov teamed up with his friend Tchigirinsky to stop Abramovich's march on the Moscow refinery.

Mr Justice Clarke noted in his High Court judgment: "In April 2004 Mr Abramovich is said to have told Mr Yuri Luzhkov, the mayor of Moscow, that the reason he had diluted Yugraneft's interest in Sibneft-Yugra was to repay Mr Tchigirinsky for his having blocked attempts by Sibneft in 2001 and 2002 to take over the Moscow oil refinery."

The reference to "diluted interest" is at the centre of the alleged scam. In September 2002, an extraordinary meeting of representatives in the partnership to drill for oil in the Priobskoye field took place in Moscow. Abramovich's Sibneft representative met an executive who had been given power of attorney to act for Yugraneft, David Davidovich. Davidovich was an adviser to Eugene Schvidler, Abramovich's closest aide. At the meeting it was decided to increase the shares in the Priobskoye partnership by bringing in three new companies, all registered offshore.

The effect of the new share distribution was to cut Yugraneft's holding from 50 per cent to five per cent. Another meeting was held a few months later. Again, Davidovich had power of attorney to act for Yugraneft. And again, Yugraneft's share of the Priobskoye venture was cut, this time to one per cent.

"We knew absolutely nothing about it," Cameron said. "People have said: 'How can something like that happen without your knowing?' Well, if you're not expecting it, why would you check? You don't check the deeds to your house to make sure you still own it."

Mr Justice Christopher Clarke disclosed in his judgement precisely how Cameron and his colleagues found out the half-share they thought they had in one of Russia's richest oilfield's was actually worth a mere one per cent.

"In December 2003," the judge said, "an employee of Ernst and Young, who were Sibneft's auditors, hinted to Mr Betsky of Sibir that the dilutions may have occurred and followed that up with an email of 6 December which suggested that he should check the ownership status of Sibneft-Yugra."

Sibir did check. What Cameron and his associates found led them to believe the company had been the victim of fraud. Sibir brought a case in the Russian courts but without success.

Cameron's people discovered their shareholding had ended up with companies registered in the British Virgin Islands. They took their argument there but again it failed. The courts decided they had no jurisdiction.

So where were the shares? Cameron says it is impossible to put a precise value on the holding without an extensive valuation but an estimate is around $2 billion, or £1.2 billion. That amount of stock cannot simply disappear. Nor did it. As the High Court case revealed, in its accounts issued in 2004, Abramovich's company, Sibneft, carried this note: "In December 2003 the company increased its share in Sibneft-Yugra up to 99 per cent for the nominal consideration." The offshore companies had been absorbed into Abramovich's oil empire.

The following year, 2005, Abramovich sold out to Gazprom, the state-backed Russian energy giant. He is believed to have received £5.5 billion for his assets, which, by then, included virtually all the Priobskoye shares. As Cameron says, his company's half-share of the oilfield is now owned by Gazprom and there is little hope of recovering it.

But if his lawyers can find a way to prove Abramovich took it improperly, he says, there may yet be a chance of claiming the value back from him. Certainly, Abramovich could afford it. One of the effects of the recent litigation was to prompt an inquiry into his wealth. It revealed that many of his companies are registered offshore, with ownership of Chelsea Football Club held by Chelsea Ltd, which is owned by Isherwood Investments, a Cypriot company, which in turn is owned by Taverham Holdings, registered in the British Virgin Islands.

The complex network of companies controlled by Abramovich holds most of his assets. The High Court case laid bare, for the first time, his vast fortune. The judge noted that his £30 million house in Knightsbridge represented just 0.5 per cent of his net worth. He has houses and property in Britain, France, Sardinia, the United States and St Barts in the Caribbean. He also has two ski chalets in Colorado, a French château and three homes in Russia. He uses two executive jets and chooses from a fleet of helicopters and cars. He also has "several yachts on which he spends a great deal of time", the High Court documents record.

But Abramovich does not spend much time in Britain. The judge said the Chelsea owner spent only 57 days here last year on visits mostly connected to football matches. This fact has proved a major stumbling block for Cameron's lawyers.

The ruling that Abramovich is not domiciled in Britain leaves them searching for a way to bring the Priobskoye oilfield case before a British court. So far, they haven't found one, but Henry Cameron is determined not to give up. "We are not done yet," he said.

Abramovich's spokesman, John Mann, declined to comment. "We'll let this ruling, and previous rulings on this case, speak for themselves," he said.