Senegalese President Abdoulaye Wade threatened Monday to pull his country's troops from the region if it was determined that the peacekeepers were ill-equipped.
"If they died because they didn't have the arms to defend themselves, I will withdraw all the Senegalese. ... I am not going to send people to be slaughtered," he said, according to Reuters.
Senegal has one of the largest contingents in the 7,000-member AU force.
AU spokesman Assane Ba said seven of those killed were Nigerian, one Senegalese, a Malian and one from Botswana.
AU officials said 23 peacekeepers were unaccounted for after the attack and were thought to be wandering around the wilderness area near the Haskanita base.
Darfur rebels are growing increasingly impatient with the AU forces, which were deployed to help protect civilians from Arab militias.
About 200,000 people have died and 2.5 million driven from their homes since early 2003, when Darfur rebels took up arms against the Sudanese government, claiming neglect. The government deployed the mainly Arab fighters to quell the revolt.
Although Sudanese President Omar al-Bashir declared a cease-fire in September, fighting has continued and impeded humanitarian aid efforts.
The weekend attack came as a group of "elders," including South African Archbishop Desmond Tutu, former U.S. President Carter, peace mediator Lakhdar Brahimi and women's and children's advocate Graca Machel, arrived in Sudan to meet with al-Bashir.
They declined to comment on their talks until the end of their visit.
Peace negotiations between the Sudanese government and Darfur rebel groups have been scheduled for Oct. 27 in Libya and have triggered more fighting as both sides try to improve their positions for the talks, according to the Associated Press.
The United Nations has approved a joint 26,000-strong AU-U.N. peacekeeping force to deploy later this month and assume responsibility for the Darfur area on Dec. 31.