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
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
Experts say that around 200,000 people were killed and 2.5 million displaced since the conflict flared in