(Recasts with developments at the United Nations; changes dateline from N'Djamena) By Patrick Worsnip UNITED NATIONS, April 17 (Reuters) - Western powers pressed Sudan on Tuesday to allow a big U.N. peacekeeping force into violence-torn Darfur, but the United Nations was struggling to put together even a smaller unit that Khartoum has agreed to. The United States and Britain said that while Sudan's acceptance on Monday of an interim U.N. reinforcement of the African Union force in Darfur was important, many more peacekeepers were needed for a total strength of up to 20,000. At least 200,000 people have been killed since 2003 in ethnic and political conflict triggered by a rebellion in the western Sudanese region. In the latest violence, a rebel group accused Khartoum's troops and militia on Tuesday of killing scores of people in a cluster of north Darfur villages -- though the army denied the charge and blamed the fighting on "normal" tribal clashes. U.S. Deputy Secretary of State John Negroponte said in Chad the African Union commander in Darfur had told him his 5,000 troops were not enough to police an area as big as France where rebels were battling Sudanese government forces and Janjaweed militias. "So even the AU as well as the U.N. believes that the size of the peacekeeping force needs to be raised from 5,000 to between 17,000 and 20,000," said Negroponte, who earlier visited Sudan. In London, British Prime Minister Tony Blair also criticized Sudan's resistance to a bigger U.N. force, saying Khartoum must be pressed to "understand its responsibilities." At the United Nations, Secretary-General Ban Ki-moon said he was encouraged by Sudan's acceptance of a "heavy support package" of 3,000 extra peacekeepers, but "the more important thing is how to implement these agreements into action". The United Nations and the African Union want to complete the interim package "and move on to the third phase, finally deploying a hybrid operation in Darfur," he told reporters after two days of talks with AU chairman Alpha Oumar Konare. The proposed 20,000-strong force is known as a "hybrid." But even the 3,000 peacekeepers Sudan has agreed to accept, who would staff control centers but not join infantry units, may take six months to recruit and deploy, U.N. diplomats say. And the African Union needs financing for two battalions ready to go in and protect the new peacekeepers. TIMING PROBLEM "I think there will be a real problem of timing ... It depends on who now comes forward as troop contributing countries," British Ambassador and current Security Council president Emyr Jones Parry told reporters. "That'll take a while to establish and then how soon can they get there? ... The hope is that the (peacekeepers) there will remain, but that others will come on board." Also unresolved is the question of funding. Cash will have to come from voluntary donations until the U.N. force arrives, at which time all U.N. members will be assessed for the financing. But first Sudan needs to allot land for camps and provide water needs. U.S. Ambassador Alejandro Wolff added a further note of caution, saying that while Sudan's letter accepting the interim package was unambiguous, "that has been the case with previous letters". "We find that the ambiguities and the clarifications are required after you take them up on their letters that said they agreed to this," he told reporters. Ban said the United Nations and the African Union were also pushing for a political settlement in Darfur and had instructed their special envoys, Jan Eliasson and Salim Ahmed Salim, to produce a "more detailed and workable road map for a political process." The report of new bloodshed in northern Darfur was made by Ibrahim al-Helu, a commander in one rebel faction of the Sudan Liberation Army, who said government troops and militia had attacked 11 villages, killing more than 70 people. A spokesman for the Sudanese army said it had no operations in that area, and these were "normal clashes between tribes". Britain's Blair said if Sudan did not agree to the U.N. package, "a strong resolution with sanctions" would be needed. The apparent deal on the interim package, however, has temporarily defused talk of sanctions and in New York, both Jones Parry and Wolff dodged questions on the issue. (Additional reporting by Stephanie Hancock in N'Djamena and Simon Apiku in Khartoum)
