World leaders are expected to threaten tougher sanctions against Zimbabwe today unless African nations take a stronger role in negotiations to remove President Mugabe.

The G8 told seven African leaders yesterday that unless they acted to deal with the “illegitimate” President, trade and investment on the continent could be hit, officials disclosed.

President Mbeki of South Africa had an uncomfortable time during the session as several leaders, including President Bush, expressed dissatisfaction at his failure to bring Mr Mugabe to book. Mr Bush called last month’s election a sham and Angela Merkel, the German Chancellor, said that she would back more sanctions.

Gordon Brown told reporters: “There is growing support for sanctions against the Mugabe regime being stepped up.”

Mr Bush said that Zimbabwe was discussed extensively at the meeting but, according to President Kikwete of Tanzania, African leaders and the G8 differed over how to respond to the crisis.

“The only area that we may differ is on the way forward,” Mr Kikwete, who is also head of the African Union, said.

“You see differently but for us in Africa we see differently, but I think again there is still room for us for discussions.”

Calling again for a unity government in Zimbabwe, he added: “I want to assure you that the concerns that you have expressed are indeed the concerns of many of us in the African continent.”

His words masked deep divisions in yesterday's meeting and growing frustration among Western governments, including the British, at the role played by Mr Mbeki.

Mr Brown hopes that the G8 will today call for tougher UN and EU sanctions and will back his call for a UN envoy to go to Zimbabwe.

Mr Mugabe was the only candidate in the run-off election after Morgan Tsvangirai, the leader of the opposition Movement for Democratic Change, pulled out because of state-sponsored violence against his supporters.

British officials came close last night to saying that Mr Mugabe should go, insisting that his election was not legitimate and pointing to the first poll in which the MDC leader finished ahead.

In an attempt to show his continued leadership in regard to Zimbabwe, Mr Mbeki flew to Harare at the weekend for a meeting between Mr Mugabe and Mr Tsvangirai. Mr Tsvangirai boycotted the meeting, saying that Mr Mbeki could no longer be trusted and that a new mediation mechanism was needed to tackle the crisis in his country. British officials believe Mr Tsvangirai's refusal to meet with Mr Mbeki shows that the South African President is no longer the appropriate mediator between the two sides.

The United States also highlighted the divergent views on Zimbabwe. "There were differences. It is fair to say that, you know, not all African leaders are in a position to support sanctions at this time,” Dan Price, presidential assistant for international economic affairs, said.

Dana Perino, spokesman for the White House, said that there was discussion among some African leaders about a power-sharing agreement for Zimbabwe and how it would be composed.

Asked how the White House would view a such a deal, Ms Perino said: “We’re waiting to see what it would look like.”

It appeared, however, that the patience of the G8 was running out.

A Canadian official quoted G8 leaders as telling their African counterparts: “The Mugabe regime is an illegitimate regime and it should not be tolerated. A number of G8 leaders drew attention to the fact that if Africa were to develop, more than just official development assistance was needed. It required trade, it required investment, and the image of Africa was suffering because of what was going on in Zimbabwe.”

An African Union summit issued a resolution last week calling for talks leading to a national unity government in Zimbabwe.But despite heightened African criticism, Mr Mugabe, who attended the AU summit, seemed unchastened.

Mrs Merkel said she was willing to ramp up pressure on Mr Mugabe, while José Manuel Barroso, the European Commission President, urged a quick solution.

"I have made very clear that I see the presidential election as illegitimate,” Mrs Merkel said. "I do not rule out further sanctions against Zimbabwe.”

Jose Manuel Barroso, the European Commission President, urged a quick solution. “There was an especially frank discussion underlining the damage that the current situation in Zimbabwe is making to the overall image of Africa and the need to find a quick solution for that very appalling and dramatic situation,” he said.

Times Recommends

• Both sides blame US for worsening relations
• Stieg Larsson: losing the plot over his cash
• Odd creature paralysed by incompatible parts