The relationship between the Movement for Democratic Change and former South African president Thabo Mbeki had irretrievably broken down, the Sunday Times newspaper reported on Sunday.

The Zimbabwean opposition party leader Morgan Tsvangirai told the newspaper that Mbeki was no longer part of the mediation efforts because he was biased and too soft on 84-year-old Robert Mugabe.

"Our relationship with Mbeki has irretrievably broken down and as far as I am concerned SA Development Community chairman and SA president Kgalema Motlanthe and the SADC itself are in charge of dealing with mediation efforts," he said.

Motlanthe, Mbeki and Mozambican President Armando Guebuza were expected in Harare on Monday to lead the negotiations.

On Sunday Mbeki's spokesman Mukoni Ratshitanga confirmed that Mbeki would be in Harare on Monday for the talks.

Ratshitanga said Tsvangirai should raise his issues concerning Mbeki with the SADC, which had appointed him as mediator.

"But if in future the SADC comes and says you are no longer mediator, then he will not impose himself."

Tsvangirai was set to attend a last-ditch meeting with the ruling ZANU-PF to form a unity government on Monday.

Tsvangirai vowed on Saturday that he would not join a coalition government if his party's demands were not fully met.

This was in contrast to Mugabe saying on Sunday that he was not prepared to make any further concessions at talks on Monday with Tsvangirai.