President Bush called on Monday for the United Nations to take over peacekeeping in the Darfur region of Sudan and promised to expedite food aid. He welcomed a proposed peace accord as "the beginnings of hope" for Darfur's poverty-stricken population.

Bush said Secretary of State Condoleezza Rice would go to the United Nations on Tuesday to press for a new U.N. resolution increasing peacekeepers.

"Darfur has a chance to begin anew," Bush said.

He also urged Congress to act on a request for $225 million in emergency food aid for Darfur, and said he was ordering the emergency purchase of 40,000 metric tons of food and was dispatching five ships to carry it to the region.

The $225 million requested in March is in addition to $215 million already contributed to the World Food Program, said Randall Tobias, administrator of the U.S. Agency for International Development.

"The rest of the world should step up," Tobias said in an interview.

The second largest contributor, he said, was Libya, which donated $4.5 million for food, followed by Canada, with $3 million.

Despite a precarious security situation about 85 percent of the food gets through to the people who need it, and the other 15 percent is held in reserve until it can be delivered, Tobias said.

Bush telephoned Sudan's President Omar al-Bashir seeking his support for a large U.N. peacekeeping force, but did not get a firm commitment, Cindy L. Courville, Bush's special adviser on Darfur, told reporters in a telephone interview.

The aim is to nearly double the 7,200 African Union peacekeeping force on the ground in Darfur and put the expanded force under U.N. control.

In New York, John R. Bolton, the U.S. ambassador to the United Nations, said the Security Council would meet Tuesday on Darfur. Bolton said the United States was circulating a proposed resolution that would extend the U.N. peacekeeping in southern Sudan to the Western Darfur region.

That 10,000-strong force is monitoring a January 2005 peace accord that ended a 21-year civil war between the Sudanese government and southern rebels that cost millions of lives.

"America will not turn away from this tragedy," Bush said, standing alongside Deputy Secretary of State Robert B. Zoellick, just back from Darfur where he played a role in arranging a Darfur cease-fire.

Bush invited other countries to also do more to help relieve famine in Darfur.

The president sought to build momentum for a peace agreement reached by Sudanese authorities and Darfur's main rebel group. The deal could help end a conflict that has killed about 200,000 people in three years and displaced some 2 million.

He praised the agreement as "a step toward peace."

"We're still far away from our ultimate goal, which is the return of millions of displaced people to their homes so they can have a life without fear," Bush added. "But we can now see a way forward."

The agreement signed Friday was between the government and the main rebel group, the Sudan Liberation Army. Two smaller rebel groups refused to sign.

On Saturday, Bush called Olusegun Obasanjo, the Nigerian president who hosted talks on Darfur, and Denis Sassou-Nguesso, the president of the Republic of Congo and head of the 53-nation African Union.

U.N. Secretary-General Kofi Annan wants Sudan to grant visas to a U.N. assessment team so it can visit Darfur and start planning for a peacekeeping force to take over from the African Union troops. Sudan has refused to allow the team to visit.

"An African Union force of about 7,200 from the region has done all it can to keep order. But they're patrolling an area nearly the size of Texas and they have reached the limits of their capabilities," Bush said.

He said the United States accounts for more than 85 percent of the food distributed in Sudan by a world food program. "But the situation remains dire," Bush said.

"The government of Sudan must allow all U.N. agencies to do their work without hindrance. They should remove the visa and travel restrictions that complicate relief efforts. And all sides must cease attacks on relief workers," the president said.