The AU, meeting in Egypt, is expected to address the re-election of President Robert Mugabe in Friday's one-candidate vote that regional monitors and Western governments have condemned as unfair and violent.

"As leaders gather for the African Union summit ... we ask that they clearly state that the results of the June 27 elections in Zimbabwe are illegitimate," the group, known as The Elders, said in a statement.

"They occurred under the cloud of targeted political violence, precipitating the withdrawal of one of the two candidates."

The group of 10 Elders includes four Nobel Peace Prize winners -- former U.S. President Jimmy Carter, former South African archbishop Desmond Tutu, former U.N. Secretary-General Kofi Annan and Bangladeshi banker and economist Muhammad Yunus.

They said the AU should appoint a special envoy to mediate an end to the crisis, create a transitional government and prepare for free and fair elections.

Opposition Movement for Democratic Change leader Morgan Tsvangirai withdrew from the poll a week ago, citing violence and intimidation.

"The crisis in Zimbabwe affects all Africans. And the fate of all Zimbabweans is on our conscience. The African Union has a commitment to good governance, justice, respect for human rights and the rule of law," the group said.