UN Secretary-General Ban Ki-moon has received a letter from Sudan's president unequivocally accepting a joint UN and African Union force to help end the bloodshed in Darfur but details must be worked out, a UN spokeswoman said Monday. A copy of the letter, obtained by The Associated Press, however, did not give Sudan's unequivocal backing to the proposal. Final approval for the 23,000-strong force faces at least one major obstacle because President Omar al-Bashir told France's foreign minister earlier Monday that he wants all the peacekeepers to come from Africa. The United Nations and the African Union have pledged to seek African troops first, but say they will use non-African troops if necessary. The UN and AU recently asked Sudan to approve troops from two African countries and two non-African countries to strengthen the beleaguered 7,000-strong AU force already in Darfur. This deployment is part of a heavy support package that will pave the way for the much larger UN-AU hybrid force. Ban told reporters he received a letter from al-Bashir a few days ago responding to a revised plan for the hybrid force to help end the four-year conflict. He said the United Nations, the African Union and Sudan were holding talks right now in Addis Ababa, Ethiopia on the proposal. "I sincerely hope that we will be able to have early resolution of this issue," he said.