The United States – backed by Britain – is pushing for "regime change" in Zimbabwe that would see President Robert Mugabe replaced by a member of the ruling Zanu-PF party.

The new president would then call a constitutional conference and organise elections to be monitored by the international community.

President George Bush is sending Walter Kansteiner, his special adviser on Africa, to the region next week. The US is persuading African leaders to back its strategy to use regional pressure to bring about the regime change.

Rather than demand an immediate re-run of the March 2002 presidential election, which international observers accused Mr Mugabe of rigging, the US is pushing a so-called "Palestinian strategy". This refers to the sidelining of Yasser Arafat in favour of the new Palestinian Prime Minister, Mahmoud Abbas.

America, Britain and South Africa have indicated that the country's former finance minister Simba Makoni is a suitable interim figure to take over from Mr Mugabe.

Mr Makoni is untainted by the worst excesses of the Mugabe regime and has publicly denounced the chaotic land seizures that have driven the country to the edge of disaster.

Tony Blair and Mr Bush have not discussed the Zimbabwe situation in their many conversations over the recent months. But Mr Blair wants the issue raised at next month's G8 summit in Evian, France. "I would like to see a bigger focus by the international community on Zimbabwe," he told the Financial Times this week.

"Now there's a limit to what you can do but I have never had a difficulty with the concept of intervention. It doesn't necessarily mean ... armed intervention, it can be diplomatic."

British ministers denied that the US plan was a payback for Mr Blair's support over Iraq. One Government source said: "If there was a quid pro quo, it was on the Middle East peace process and the publication of the road-map."

African leaders, including South Africa's President, Thabo Mbeki, have openly supported Mr Mugabe despite widespread international condemnation. They have also succeeded in undermining British attempts to isolate his regime internationally, most recently insisting that he be invited to the Franco-Africa summit organised by President Jacques Chirac.

Over the past three months Mr Mbeki's views on regime change have changed, according to Mr Kansteiner. South Africa now acceptsMr Mugabe should be edged aside, he said.

Other influential African countries including Botswana, Mozambique, Senegal, Ghana agree that Mr Mugabe's removal from power is the only realistic step towards resolving the deepening crisis in Zimbabwe, which threatens to plunge the region into humanitarian and economic chaos.

Mr Mbeki believes it would be easier to lobby international support for Zimbabwe with a new leader. Mr Mbeki, Nigerian leader, Olusegun Obasanjo, and Malawi's President, Bakili Muluzi, arrive in Zimbabwe on Monday for talks with Mr Mugabe and opposition leader Morgan Tsvangirai.