Sudan has agreed to let 3,000 UN peacekeepers deploy in Darfur with attack helicopters, opening the door to the first significant UN force to help beleaguered African Union soldiers who have been unable to halt the region's four-year war. After five months of stalling and back-tracking, the government called Monday for speedy deployment of the UN contingent and hinted it could approve an even larger 20,000-strong force, which the African Union has been seeking. UN Secretary-General Ban Ki-moon called the agreement "a very positive sign" and said the UN and the African Union will "move quickly" to prepare for deployment of the 3,000 peacekeepers and the 20,000-strong AU-UN force. The United Nations has no standing army. Ban urged UN member states to contribute troop and police quickly for Darfur, but it likely will take months before the UN contingent is on the ground. The Security Council reacted swiftly, welcoming Sudan's decision to accept the UN's heavy support package to beef up the AU force: 3,000 UN troops, police and other personnel along with logistical and aviation equipment - including six attack helicopters which Khartoum initially rejected. The council called on the government to facilitate "the immediate deployment of the package" followed by the deployment of the 20,000-strong AU-UN force. It also called for "an immediate cease-fire, a reinvigorated political process, (and) an improvement in the humanitarian situation..." Britain's UN Ambassador Emyr Jones Parry, the current council president, said he sent a letter to the secretary-general late Monday on behalf of the council asking Ban to seek General Assembly approval to fund the UN share of the heavy support package. Sudanese President Omar al-Bashir has repeatedly rejected a UN force. But he has come under increasing pressure from the United States, the European Union, some Arab and African countries, and recently-close ally China, which buys two-thirds of Sudan's oil exports and sells Khartoum weapons and military aircraft. Though al-Bashir's government has a history of finding loopholes in agreements with the UN and others, the deal reached Monday appeared to be a significant step forward in bringing a more effective peacekeeping force to Darfur. Nonetheless, US diplomats and UN officials said they remain cautious until the UN peackeepers are on the ground in the vast western province where more than 200,000 people have been killed and 2.5 million have been displaced since the conflict began in 2003. "We'll see whether they've agreed when they actually start to deploy," acting US ambassador Alejandro Wolff told reporters.