Sudan was said to have begun imposing restrictions on a government-supported militia that has killed or expelled hundreds of thousands of Africans from their homes.

U.S. officials said that in May the regime of President Omar Bashir began to impose limitations on operations of the Jinjaweed militia. They said the restrictions were decided amid heavy U.S. and international pressure in wake of a ceasefire agreement in the western province of Darfour.

"The government has reversed its position in the last couple of weeks in terms of access, and they are beginning, it appears, to begin to put some constraints in some areas on the Jinjaweed militia," Andrew Natsios, U.S. Agency for International Development director, said. "The Jinjaweed militia continues to commit atrocities, albeit on a reduced scale."

At a briefing on Tuesday, Natsios said the Arab-composed Jinjaweed continues to operate in Darfour and attack civilians, Middle East Newsline reported. He said this has hampered plans to transport relief supplies to refugees in Darfour and neighboring Chad.

The United Nations reported that about 1 million Darfour residents have been forced out of their homes during the civil war over the last year.

About 200,000 Darfour residents fled into neighboring Chad as the Jinjaweed, backed by Sudanese troops, torched villages and killed civilians.

[On Tuesday, fresh fighting was reported in Darfour near a key town.

Sudanese officials asserted that rebels had launched an attack.]

Officials said the April ceasefire in Darfour remains to be fully implemented. But they said violations of the agreement appear to have been reduced over the last two weeks.

"I know sometimes decisions are made in Khartoum that are always not completely communicated down to the grassroots level and it takes a while to do that," Natsios said. "We hope that will happen quickly, but we're running out of time."

Officials said the United States provides 55 percent of the relief aid allocated for Darfour. They said the Khartoum government has not implemented its pledge to allow relief workers access to refugees.

"We are seeing improvements in access, but that doesn't mean we have anything close to 100 percent access," Roger Winter, assistant AID administrator, said. "In south Darfour the rains have already begun. By some point during this month, all of Darfour will be subject to rains. What does that mean for this population that has not been being fed properly for, in most cases, three, four, five months, maybe up to nine months, okay, where their body is already weakened?"

Officials said most Darfour refugees have refused to return to their homes out of fear of a resumption of attacks by the Jinjaweed. They said many have either remained in Chad or resettled in cities.