JOHANNESBURG, SEPT. 24 -- The United States and Angola announced today that they have agreed to create "relief corridors" into isolated areas of war-torn southern Angola where 250,000 people are said to be in danger of immediate starvation.

The agreement, disclosed in Luanda and Washington, will allow U.N. relief agencies, private volunteer groups and the Geneva-based International Committee of the Red Cross to transport emergency relief supplies across Namibia into territory controlled by the Angolan government and that held by the National Union for the Total Independence of Angola (UNITA), a U.S.-backed rebel group led by Jonas Savimbi.

"The two sides agreed on the need for prompt and efficient delivery of relief supplies to all affected populations in Angola," a joint statement said.

"The Angolan side advised the U.S. side of its decision to permit relief supplies to enter Angola from neighboring states by the fastest and most efficient routes and indicated that this decision had already been communicated to the government of Namibia," it added.

The Angolan government also said it had told the United States that it would permit UNICEF and the World Food Program to "establish operational contacts with concerned parties in Angola to initiate the relief effort," an apparent reference to UNITA, according to U.S. officials.

Two years of drought and 15 years of fighting between the Angolan government and Savimbi's rebels have caused severe food shortages in southern Angola, where 2.5 million people live. The Office of U.S. Foreign Disaster Assistance today reported that estimates of famine-related deaths in the drought-affected region ranged from 3,800 to 10,000 during the first eight months of this year.

The agreement was worked out at an undisclosed location between delegations led by Andrew Natsios, director of the U.S. disaster assistance office, and the Angolan chief of staff, Gen. Antonio dos Santos Franca. Natsios recently returned to Washington from a visit to Luanda, UNITA-controlled territory in southern Angola and Windhoek, Namibia, where he may have met with Franca.

The United States has no diplomatic relations with Soviet- and Cuban-backed Angola, and the two governments have been at odds over U.S. military assistance for Savimbi's rebel movement since 1986.

In telephone interview, Natsios said at least five relief corridors, or "peace corridors," would be established. Three would lead by road from the government-held Angolan port cities of Luanda, Namib and Lobito into the worst-affected areas in southern Angola. Two rail and land routes will lead from the South African-controlled port of Walvis Bay in Namibia north into southern Angola, with one going directly into UNITA territory.

Natsios said that Namibian President Sam Nujoma had assured him he had "no problem at all" with U.N. and other international relief agencies using Namibian rail and land routes to reach southern Angola.

Natsios said he was "very pleased" with the agreement but warned that "it remains to be implemented."

"Something has happened in writing. Now it has to happen on the ground," said Natsios, who indicated it is now up to the United Nations to take the lead in working out the details.

The United Nations has increased its estimate of the number of people requiring emergency assistance from 1.5 million to 1.9 million based on partial assessments of the affected areas. The U.S. disaster assistance office estimated 250,000 of those were "immediately at risk of starvation."