"A government of national unity does not address the problems facing Zimbabwe or acknowledge the will of the Zimbabwean people," Tsvangirai told reporters after a meeting of his party's national executive committee.

Speaking after African Union leaders called for the formation of a national unity government, the Movement for Democratic Change leader said the AU had failed to acknowledge that he won the first round of Zimbabwe's election before Mugabe staged a one-man run-off last Friday.

"The resolution does not recognise the illegitimacy of the June 27 election and the fact that most African leaders refused to recognise Mugabe as head of state," he said.

"The resolution endorses the concept of a government of national unity without acknowledging that the MDC, as the winner of the last credible election, on March 29 should be recognised as legitimate government of Zimbabwe."

Tsvangirai said his party was committed to negotiations on the country's crisis but these should be on the basis of finding a transitional agreement that would lead to a new constitution and fresh elections.

"While the MDC remains committed to negotiations this must be based on the March 29 result and must move towards a transitional agreement," he said.

"Our commitment to a negotiated settlement is not about power-sharing or power deals but about democracy, freedom and justice."

Mugabe's Information Minister Sikhanyiso Ndlovu had earlier told AFP that the government welcomed the AU's call and said that it was "ready for dialogue with whoever, a dialogue for national unity in Zimbabwe."

Tsvangirai beat Mugabe into second place in the first round of voting in March when the MDC also wrested control of parliament from the long-ruling ZANU-PF party.

But he pulled out of last Friday's run-off five days before polling after nearly 90 MDC supporters were killed in attacks the opposition blamed on pro-Mugabe militias.

In his press conference Tsvangirai said that there had to be an end to attacks before any talks could take place with Mugabe's party.

"If dialogue is to be initiated it is essential that ZANU-PF stops violence," he said.

Tsvnagirai also reiterated MDC calls for an African Union mediator to be appointed saying that the region's current pointman South African President Thabo Mbeki was considered biased towards Mugabe.

"We need an expanded mediation team which includes a representative from the AU. It is our position that unless the mediation is expanded to include at least one permanent representative from the AU and the mediation mechanism is changed no meaningful progress can be made towards resolving the Zimbabwean crisis," he said.

"We have said that President Mbeki you have taken all these years and we are not happy with you. What we want is to get another AU partner to come here and solve this problem."