HARARE, Zimbabwe -- Zimbabwean opposition leader Morgan Tsvangirai on Wednesday rejected talks on a unity government, saying President Robert Mugabe must first stop violence and accept him as the rightful election winner.

African Union leaders called at a summit on Tuesday for the two sides to negotiate to end the crisis after Mugabe's re-election in a June 27 ballot that was boycotted by the opposition and dismissed by much of the world as a sham.

Tsvangirai said his Movement for Democratic Change should be the legitimate government after beating Mugabe's ZANU-PF in parallel parliamentary elections.

Mugabe's officials earlier welcomed the call from African leaders for talks on a power-sharing government.

Tsvangirai said talking to Mugabe would be meaningless unless the African Union sent a permanent envoy to expand mediation efforts by South African President Thabo Mbeki.

Despite the AU support for a power-sharing deal, disagreement over who should lead the government could prove an insurmountable obstacle.

Western countries are pushing for UN sanctions on Zimbabwe's leaders and a draft U.S. resolution called for a UN travel ban and asset freeze on Mugabe's inner circle. But some countries on the Security Council have shown little appetite for such measures, which are already imposed by Europe and the United States.