The government ordered the suspension, except for humanitarian activities, after the United Nations in El Fasher in North Darfur permitted a U.N. helicopter on Saturday to transport a rebel leader from one of the armed groups "bent on wrecking peace," according to a Foreign Ministry statement quoted Sunday by the official news agency SUNA.

The Sudanese government signed an agreement May 5 with one rebel faction of the Sudan Liberation Army but another faction of that group and the Justice and Equality Movement have refused to sign the accord.

U.N. spokesman Stephane Dujarric said the U.N. Mission in Khartoum reported Monday that "all these restrictions that had been called for by the government have now been removed."

"The crux of the matter was related to flight manifests, and the regulation by which the U.N. needs to communicate to the Sudanese authorities the manifest on its flights within Sudan," he said. "I think there were some issues with a particular flight and we're looking into it."

Dujarric refused to say whether a rebel leader had been aboard a U.N. flight. The U.N. Mission in Sudan "said it would look into this issue of the flight manifest," he said.

The flap came as tensions between the U.N. and Khartoum have been building over the deployment of a U.N. peacekeeping force in the troubled western region of Sudan. The U.S. and the U.N. want U.N. peacekeepers to take over from an African Union force. But last week, Sudanese President Omar al-Bashir vowed he would never allow that.

According to a statement by the Sudanese Foreign Ministry on Sunday, Sulieman Jamous, the leader of a Sudan Liberation Army faction who did not sign the May 5 Darfur Peace agreement, purportedly flew from El Fasher to Kordufan on a U.N. helicopter.

The ministry's order affected all U.N. operations in Sudan except activities carried out by the U.N. children's agency, UNICEF, and the World Food Program.

"I don't think it had any specific effect on the (U.N.) operations due to the short time lag between the announcement and the fact that the situation's now been reversed," Dujarric said.

The Darfur conflict began in early 2003 when members of ethnic African tribes rose in revolt against the Arab-led Khartoum government. Sudan's government is accused of responding by unleashing Arab militias known as the janjaweed who have been blamed for the worst atrocities. Khartoum denies any involvement, but has committed to disarm the janjaweed under the peace deal.

Nearly 200,000 people have died since the conflict began, some 2 million have been rendered homeless, and the fighting has spilled across the border into Chad.

On Friday, U.N. Secretary-General Kofi Annan said he plans to meet the Sudanese president at upcoming African Union summit to press for a U.N. takeover of peacekeeping from the African organization.

The African Union has said it cannot handle a long-term peacekeeping operation and wants its 7,000-strong force replaced by U.N. peacekeepers. The U.N. has envisioned taking over in early 2007 and wants to beef up the poorly equipped AU force in the interim. But the handover is contingent on approval by the Sudanese government.