U.N. Secretary-General Kofi Annan called for a more mobile and sophisticated peacekeeping force in Sudan's Darfur region as the Security Council mulled turning an African Union mission into a U.N. operation.

Clashes continue in the region despite the presence of 7,000 African troops sent to enforce an April 2004 ceasefire.

The mission, a first for the 53-nation African Union, is seen as a test of its ability to resolve the continent's conflicts. But the Africans have said they lack the international support, financial and logistical, to be successful.

"What we need to do is to find a way of improving security — immediate improvement in security — working with the African Union forces," Annan said Thursday.

If the United Nations does take over the peacekeeping effort, he said he would ask the United States, European countries and other developed nations to participate.

"Whichever force is there ... has to be mobile, has to have tactical air support, must have helicopters and ability to respond very quickly, so it would be a different type of structure," he said. "And we will need very sophisticated equipment, logistical support."

Annan discussed a possible U.N. takeover with Security Council ambassadors at their monthly lunch. The AU must first decide how long it can sustain the operation and how long it wants to stay, he said.

Decades of low-level tribal clashes over land and water erupted into large-scale violence in early 2003 when ethnic African tribes took up arms, accusing the Arab-dominated central government of neglect. The government is accused of responding by unleashing Arab tribal militias known as Janjaweed to murder and rape civilians and lay waste to villages. It denies the charge.

An estimated 180,000 people have died in the upheaval — many from hunger and disease — and about 2 million have been displaced.

The government and rebels agreed to a ceasefire in April 2004 but attacks continue, Annan said. The United Nations is feeding 3 million people in Darfur, up from 1 million not long ago, and may have to do so for another year, he said.

Also looming is the threat of war between Sudan and neighboring Chad, which has taken in some 200,000 refugees from the two-year conflict. Chad and Sudan have traded accusations of supporting rebel groups.

The Sudanese government has in the part refused to accept troops from outside Africa. "But I think we have gone beyond that now," Annan said.

He said AU ministers discussed the issue Thursday and African leaders will likely make some decisions during their Jan. 16-24 summit in the Sudanese capital, Khartoum.

In a report Wednesday, the Boston-based Physicians for Human Rights said U.N. peacekeepers should be deployed to Darfur because the AU force lacks the resources to be effective.

"A lot of people in the AU are reluctant to see the mission shift because it would be seen as an AU failure," U.S. Ambassador John Bolton said earlier this week. "We don't see it that way. ... What we're looking for is the mechanism to provide security in Darfur."

Britain's U.N. Ambassador Emyr Jones Parry said there was support in the Security Council for a U.N. takeover.

"We're quite clear that's what we need to do if the African Union agrees," he said after Thursday's lunch. "But the African Union must be brought to agree."

The African Union has money to operate until March, and AU Chairman Alpha Oumar Konare has indicated the force wants to stay on for nine to 12 months.

The AU mission in Darfur began in 2004 with less than 500 peacekeepers and has grown with financial and logistical support from the EU, the United States and others.

Annan said the time had probably come for another donors conference to assist the African Union, noting that if the U.N. were to take over it could not do so by March.