The United Nations said Thursday it would send a team to Darfur to prepare for a peacekeeping mission, but Sudan said any U.N. role in the troubled western region would be smaller than some Security Council members want.

"This joint mission of the United Nations and the African Union will start with detailed and wide-ranging consultations in Khartoum," said Lakhdar Brahimi, a special envoy to the secretary general.

Brahimi called the mission an "important step" in cooperation between the international community and Sudan, which had previously barred the assessment team. In a resolution last week, the U.N. Security Council gave Khartoum one week to allow the assessment team to go in.

CountryWatch: Sudan

But shortly before Brahimi spoke at a news conference, Sudanese Foreign Minister Lam Akol said Sudan wants a potential U.N. force to play a far smaller role in Darfur than some members of the Security Council have envisioned.

"Any forces if that is agreed upon would be a force for supervision and not a force for peace implementation," he said.

Last week, the U.N. Security Council resolved that a large U.N. force should take over peacekeeping in Darfur from the under-equipped African Union mission that has failed to end the three-year conflict.

Sudan has long resisted allowing U.N. peacekeepers into Darfur, arguing the conflict is an African problem that should be handled by troops from the continent.

Earlier Thursday, Bbrahimi discussed the proposed peacekeeping mission with President Omar al-Bashir. The meeting took place a day after the speaker of Sudan's parliament, which is dominated by al-Bashir's party, said he would oppose a U.N. military presence in Darfur.

"The National Assembly rejects any role for foreign forces in Darfur," speaker Ahmed Ibrahim Tahir said, according to the official Sudan News Agency.

Brahimi said the assessment team will visit Darfur to review the needs of the African Union peacekeeping force in the region, and also discuss requirements for a transition to U.N. control.

Separately Thursday, the U.N. mission to Sudan said that government forces were increasingly tackling groups that hijack NGO vehicles in North Darfur, and have detained militiamen.

In a report last week, U.N. Secretary General Kofi Annan accused Khartoum of violating international humanitarian law by barring the delivery of fuel, food and relief aid to civilians in Darfur.

More than 180,000 people have died, mostly from disease and famine, and 2.5 million people have been displaced since February 2003 when a rebellion by Darfur's ethnic Africans provoked a devastating counterinsurgency in which pro-government militia committed widespread rape, arson and murder.

Brahimi arrived in Sudan on Tuesday with deputy head of U.N. peacekeeping operations, Hedi Annabi, in a bid to persuade the government to implement the Security Council resolution and follow through on the May 5 peace accord in Darfur.

A former foreign minister of Algeria, Brahimi is a widely experienced U.N. troubleshooter and previously served as Annan's special envoy to Afghanistan and Iraq.