Secretary-General Kofi Annan has called a high-level meeting to discuss formation of a "hybrid" peacekeeping force for Sudan's war-ravaged Darfur region. Sudan remains adamantly opposed to allowing an international force in Darfur.

On a day when as many as 40 civilians were reported killed in Darfur, Secretary-General Annan invited Sudanese officials for talks with representatives of the United States, the European Union, Russia and China.

Mr. Annan's spokesman says the secretary-general hopes to win Sudan's backing for what is being called a "hybrid" force that would be strong enough to quell the three and a half years of violence in the vast western region. Human rights activists say more than 200,000 Darfurians have died, many of them in massacres the United States has called genocide. Two and a half million more people have been forced to flee their homes.

A 7,000 - strong African Union force has struggled to police the region, which is the size of France. Some of the worst violence has been blamed on Arab militias called janjaweed. Investigators accused Khartoum of backing the janjaweed, a charge the government denies.

Mr. Annan called the high-level meeting for Thursday in the Ethiopian capital, Addis Ababa, where the African Union is holding a series of discussions this week on Darfur. U.N. spokesman Stephane Dujarric says the meeting is aimed at moving the peace process forward decisively.

"The situation in Darfur is critical as we've been reporting every day," said Stephane Dujarric. "We continue to strengthen the current African Union force with a package approved by both the Security Council and the government of Sudan, a $21-million package. As the secretary general said before he left, we're also looking beyond for what should be a credible force on the ground."

The meeting was called as a U.N. Security Council delegation cancelled a scheduled visit to Addis Ababa to participate in the AU talks. U.N. officials said the mission was abandoned because of disagreements about its authority.

A senior U.N. official attending the Addis Ababa talks, Assistant Secretary General for U.N. Peacekeeping Hedi Annabi Monday said Sudan had agreed to allow tens of millions of dollars in improvements for the AU force in Darfur. Sudanese officials, however, remain strongly opposed to allowing U.N. command of the force.

Mr. Annan made his "hybrid" force proposal in a report timed for release before the Addis Ababa meetings. The report describes the force as "predominantly African" in character, but with more money, manpower and equipment to protect Darfur's civilian population.