African Union leaders have opened a summit in Sudan's capital, Khartoum, amid a row over Sudan's bid to chair the body for the next year.
The AU members face a number of tough issues
Sudan is the only country to put its name forward, but some fear its human rights record will damage the AU.
There are fears that Sudan's leadership could set back efforts to reach a peace deal in its western region of Darfur.
Five countries have asked Sudan to withdraw, Reuters reports. Sudan says it has the backing of 12 other nations.
Traditionally the host of the 53-nation AU summit takes over in the chair.
'Chaos in Darfur'
But human rights groups say it will be a disaster if Sudan is chosen. They cite the crisis over Sudan's Darfur region and allegations that Khartoum-backed militias have been involved in murder, rape and other atrocities.
More than 200,000 people have been killed in Darfur in the past three years and two million people have been forced from their homes.
Rebels from the Darfur region have said they will pull out of peace talks if Sudan takes over at the AU.
Since the AU has a peacekeeping force in Darfur and mediates in the crisis, there are concerns of a conflict of interest if Sudan is in the chair, says the BBC's Adam Mynott in Khartoum.
"As far as the security on the ground is concerned, there is chaos, in particular in west Darfur where there are many parties fighting," the head of the UN mission in Sudan, Jan Pronk, said.
"There are still attacks by militias on civilians," he said.
However, he has said the choice of AU chairman should be left to the AU itself.
Africa is split down the middle over Sudan's candidacy, says our correspondent.
Sudan says it has won the unanimous backing of 12 East African nations.
However an AU official told Reuters that five heads of state had met Sudanese President Omar Hassan al-Bashir on Sunday and told him "there was a consensus that he should withdraw".
The countries were not named, except that Nigeria, the current AU president, was said to be among them.
"It is looking like the compromise is for [Nigerian President Olusegun] Obasanjo to stay because then Bashir will save some face," the official said.
An alternative suggestion is that a central African candidate, possibly Congo Republic, take the chair.
A meeting of human rights delegates in Khartoum was broken up on Sunday by Sudanese police, who detained them and took their photographs.
"This kind of heavy-handed behaviour shows why Sudan was not the right country to hold the summit and also shows the president of Sudan isn't the correct person to lead the African Union," Human Rights Watch spokesman Reed Brody said.
Zimbabwe's Robert Mugabe is among those attending the summit
Apart from the row over the leadership, AU members face matters ranging from armed conflict to famine, disease and economic development.
One of the leading issues at the summit will be whether Senegal should extradite Chad's former leader Hissene Habre to Belgium, which has issued an arrest warrant for him alleging crimes against humanity.
Senegal has arrested Mr Habre, but said it would ask the AU to decide whether he should be handed over.
The security deterioration in the Ivory Coast is also expected to be on the agenda.