Mezni said the AU had sent an investigation unit to Sirba, and angry villagers later tried to prevent the team from leaving.

"The African Union is under threat by the local population in Sirba. There are efforts now to allow the team to leave the area," he said.

"We appeal to everybody to know that the AU is in Darfur to help the people and restore stability and reach peace. We are not in Darfur to be part of the conflict."

Earlier, armed men riding on horses and camels attacked Sirba in November, killing up to 30 villagers and wounding 40.

The AU maintains an under-funded and ill-equipped 7,000 force in Darfur that has failed to stop the violence.

Experts say that around 200,000 people were killed and 2.5 million displaced since the conflict flared in Darfur in 2003 when rebels took up arms against the government, charging it with neglect.