The pan-African body also renewed its call for the United Nations to take over the operation, despite fierce opposition from Khartoum, which wants the AU force to leave unless its mandate is extended, officials said.
At a special meeting of the AU Peace and Security Council, diplomats agreed the mandate of the African mission in Darfur should expire on September 30 as initially foreseen, but decided its future could be re-visited.
The development followed a Sudanese government request for "clarification"
on the expiration of the mandate of the AU force and the cash-strapped AU's
desire to hand it over to the United Nations.
Peace and Security Council commissioner Said Djinnit told reporters that
African foreign ministers would meet in mid-September on the sidelines of the
annual UN General Assembly to consider the Sudanese positions.
"We are not in a position to tell the world whether we are going to stay or
leave, but we stick to our decision as it was decided by the heads of state
that there is a need to transfer the peacekeeping duties to the UN," he said.
"We are going to meet on September 18... to consider the request of the
Sudanese government for clarification," Mr Djinnit said after the meeting at AU
headquarters in the Ethiopian capital of Addis Ababa.
Facing soaring costs and uncertain donor commitment to keeping the
operation afloat, African leaders decided in June to wrap up the AU Mission in
Sudan (AMIS) at the end of September and turn it over to the United Nations.
But despite mounting international pressure, including a UN Security
Council vote last week to authorise the force, Sudan has refused to accept it
and on Sunday said AU troops would have to leave the country without a new
mandate.
Mr Djinnit hinted that a mandate extension was possible, but diplomats said such a move was highly unlikely without a major infusion of donor funds.
Monday's AU Peace and Security Council meeting came after Sudan asked the African Union to explain the Darfur mandate's expiration and its call for a UN force over its strong opposition.
But Sudan's envoy to the African Union, Al-taib Ahmed, said reports that
Khartoum had demanded the automatic withdrawal of the AU operation by the end of the month were incorrect.
"What is reported in the media is totally distorted," Mr Ahmed told reporters.
"What the Sudanese government is asking for is a clarification from the AU
if it is unable to continue its mission after September 30, and an explanation
of the repeated statements of the AU on the transfer of mission to the UN."
Earlier on Monday, Khartoum said it had given the African Union a week to
decide on the mandate of the Darfur force.
Sudan's minister of state for foreign affairs, Ali Ahmad Kerti, said his
government "still supported the presence of AU forces in Darfur and had asked for financial aid for them," according to a government statement.
"But the Peace and Security Council, without consulting the Sudanese
government, is insisting on putting a deadline on the role of African forces in
Darfur and transferring the mandate to the UN," he said.
Many analysts and aid workers believe the AU's embattled 7,000-strong
Darfur force is ill-equipped and lacks the resources to provide adequate
security in the region and are calling for the United Nations to take over the
mission.
The combined effect of war and famine in Darfur has left up to 300,000
people dead and displaced 2.5 million in three and half years of civil war
pitting the Sudanese government and allied militias against ethnic minority
rebels.