U.N. Secretary General Kofi Annan is urging the Security Council to act quickly to protect civilians in Sudan's troubled Darfur region. The United States is preparing to introduce a Council resolution on Darfur this week, but sanctions against the Khartoum government are unlikely.

With U.N. observers in Darfur reporting fresh attacks by Arab militias on civilians, Secretary General Annan urged Sudan to accept a larger international protection force.

The Security Council earlier ordered the Khartoum government to rein in the militias - known as Janjaweed. But Mr. Annan says the African Union (AU) force sent to ensure compliance was far too small.

"In the study we did with the African Union, we indicated the number of troops or observers they will require, because the original number was woefully inadequate, so for them to be effective, and they agree with us, they need to get in higher numbers, and logistical and financial support they need," he said.

U.N. diplomats say that any Security Council resolution on Darfur is unlikely to include the threat of sanctions against Sudan. The Secretary General's envoy to Sudan, Jan Pronk, last week called for the international presence in Sudan to be increased by several thousand, but he downplayed the need for sanctions. The African Union has about 80 military observers in Darfur, protected by just more than 300 soldiers, monitoring a largely ignored cease fire.

Separately, Secretary of State Colin Powell is scheduled to speak out on the atrocities in Darfur later this week. The Bush administration is considering whether to label the activities of the Janjaweed as genocide.

Washington's U.N. Ambassador, John Danforth, last week accused Sudan of using attack helicopters against Darfur villagers. He criticized U.N. officials, saying they were wrong to suggest that Sudan's government should have a say in deciding whether to increase the size of the international force in Darfur.

Ambassador Danforth said the people of Darfur have no confidence that the Khartoum government would protect them.

Janjaweed militia attacks have left much of the Darfur region in ruins. Tens of thousands of residents of the remote region have died in the past 18 months, and another 1.2 million people have fled their homes in what U.N. officials have described as the world's worst humanitarian disaster.