Rebels took hostage 18 members of an African Union team in Darfur on Sunday, but released most of them after negotiations with the 53-nation organisation, officials said. They were abducted by a splinter group a day after the first AU peacekeepers were killed in an ambush blamed on another guerrilla force in the western Sudanese region, where non-Arab rebels took up arms against the central government in 2003. "Most have been released but it is not clear how many," said AU spokesman Noureddine Mezni.The freed hostages, who had been held near the border with Chad, were on their way back on foot to the area's main town. Mezni, who did not give details on the talks with the kidnappers, said earlier reports had indicated that 16 of the 18 were being freed but that was not yet confirmed.