Keep your promise on Africa, Tony

With the passion and faith of an evangelical Christian the Prime Minister has told us that the Dark Continent is a "scar on the conscience of the world... we could heal it". In the last four months he's dispatched Clare Short and Jack Straw as his missionaries to figure out how to close the scar before it becomes "deeper and angrier". This week he will place his healing hands on the continent himself. He'll be wasting his time; he's going to the wrong places.

Tony Blair's itinerary is secret but it is believed to be taking him to Nigeria, Senegal, Ghana and possibly Sierra Leone. Mr Blair is right to be worried about Africa. From a moral perspective the fact that the continent has been hurtling backwards, by every measure of the human condition, for 30 years is partly the fault of the West. We should help to put it right. There is also a pragmatic case for healing Africa's wounds. If we don't, we're going to be swamped by refugees from misery on a scale so far unimagined.

Already criticised at home for foreign jaunts which relieve him of the grubby burden of sorting out health, transport, and education, Mr Blair is unlikely to be much help to Africa.

He is much more interested in lofty concepts than practical realities. His thinking has been dominated by Thabo Mbeki, South Africa's president and author of a scheme called the "New African Initiative", in which good governance is rewarded with trade concessions and debt forgiveness.

Selling this rather unoriginal idea to the G8 nations is going to be hard when Mr Mbeki is set to spend $5.7 billion on jets, helicopters and navy ships - many of them made in Britain - which South Africa simply does not need.

Yesterday Wiseman Nkhulu, Mr Mbeki's economic adviser, was briefing journalists on Mr Blair's trip. No mention was made of the £200million being spent by Africa on British arms this year.

There is no doubting that Mr Blair is more interested in Africa than any Prime Minister since the Boer War. On Tuesday Chancellor Gordon Brown announced a £10million education fund for primary school children and pledged to ring more out of the rich nations at the G8 summit in Ottawa next weekend.

But the Prime Minister has said nothing about South Africa's wasteful defence spending. He is also steering well clear of Rwanda, Burundi and the Democratic Republic of the Congo, which are being torn apart by war and gouged of minerals by carpetbaggers.

And this week he'll skip around Zimbabwe, where half a million people face starvation within eight weeks because President Robert Mugabe has wrecked the commercial farming sector. Oh, and where 30,000 whites, many of them of British descent, are being ethnically cleansed as a matter of government policy.

The Prime Minister's decision to stay away from these areas is a waste of a golden opportunity for him to prove he has not been talking in tongues when speaking of Africa. Last October he told the Labour Party Conference: "I tell you, if Rwanda happened again today as it did in 1993, when a million people were slaughtered in cold blood, we would have a moral duty to act there also."

He's right that we should never allow it to happen again. The memory of the murder of 37,500 Tutsi men, women and children a day, mostly with clubs and machetes, should not be allowed to fade any more than the Holocaust should be forgotten.

But when he was a front bench member of the Opposition, Mr Blair didn't raise a peep of protest at the withdrawal of United Nations troops from Rwanda just as the killing got under way. He didn't call for the dispatch of paratroopers to prevent the well planned annihilation of a whole race.

Indeed, the Prime Minister doesn't even have his dates straight. The genocide was in 1994.

The killing led to the destablisation of the Congo and a war which has has sucked in Angola, Zimbabwe, Rwanda, Burundi and Uganda.

Joseph Kabila, Congo's president, is an impressionable man of 33, keen to please older statesmen. He also happens to be half Tutsi. Mr Blair might be just the man to persuade him to make peace with his neighbours, end support for those responsible for the Rwanda genocide, and end an absurd conflict in which three million people have perished.

Last October Mr Blair boasted: "We were there in Sierra Leone when a murderous group of gangsters threatened its democratically elected government and people." He should be proud of this. In Zimbabwe a murderous group of gangsters, who also happen to be the government, are threatening their own people with rigged elections, chaos and starvation.

It is inconceivable that a British Prime Minister should visit the former Rhodesia at this time. But he could put in some useful hours meeting Zimbabwe's neighbours who have been less than critical of Mr Mugabe's destructive policies.

Mr Mbeki in particular has been reluctant to put any pressure on Mugabe, fearing his own position could be undermined by more radical elements in the African National Congress. Mr Blair should use his African trip to persuade his friend the South African president to put the squeeze on Mr Mugabe before it is too late for any "New African Initiative".

So far Zimbabwe's neighbours have been criminally stupid. They will bear the brunt of the chaos that threatens to engulf the country, where already famine looms and government-sponsored militia death squads are on the prowl.

By the end of next month the infectious anarchy which has engulfed much of Africa could pour across the Limpopo river. And another great swathe of the continent will become a scar on Mr Blair's conscience.