(Adds complaint of sexual assault) By Opheera McDoom KHARTOUM, Jan 23 (Reuters) - The African Union has confirmed Sudan's army bombed two villages in North Darfur, violating ceasefire agreements and jeopardising efforts to revive a stalled peace process. Separately, the United Nations reported an assault on aid workers, saying 20 AU, U.N. and aid agency staff were arrested at a social gathering and five were beaten by police in Darfur, with some sustaining serious injuries. One U.N. staff member said she was sexually assaulted by police. In the first independent confirmation of rebel reports that the government bombarded their positions in Anka and Korma on Jan. 16 and 19, the AU condemned the attacks. "The (AU) ceasefire commission is once again calling on all parties to refrain from any activities that will jeopardize the peace process," the statement sent late on Monday said. Rebels are trying to hold a conference in Darfur to unify their position ahead of a renewed push for peace talks. They want government guarantees that the conference will not be attacked, but the army has three times bombed rebel positions in the past two months, the AU says. Sudan's armed forces spokesman denied all reports of bombing in the past two months. Experts estimate some 200,000 people have been killed and 2.5 million forced from their homes in four years of rape, pillage and murder in Darfur, violence Washington calls genocide. Khartoum denies genocide and says the Western media overplay the conflict. The International Criminal Court is investigating alleged war crimes in the region. BEATEN Rebels also accused the government of bombing their positions in Ein Sirro on Jan. 20, killing 17. The AU has not confirmed that bombing but a U.N. bulletin seen by Reuters on Tuesday said it also had reports of bombing at Ein Sirro, which killed two civilians and a large number of cattle. The U.N. bulletin also said it was investigating the arrest and assault on five of its staff and 15 others by police in South Darfur's state capital Nyala on Jan. 19. "The U.N. staff were beaten both with hands and with rifles," Edward Carwardine, a spokesman for the U.N. children's agency UNICEF, said on Tuesday. The staff were international, he added. "One of our U.N. staff has made a complaint of a sexual assault against her," Cawardine later added. An international aid worker last year working for Medecins Sans Frontieres was seriously sexually assaulted in Darfur. The U.N. statement added: "Several of the detained staff sustained serious injuries, some of which required treatment at the U.N. clinic in Nyala." All were subsequently released. "The United Nations will also officially protest to the government of Sudan the assault of the staff by local police, in violation of basic principles of rule of law and due process," it said.
