MONROVIA, LIBERIA, JULY 25 -- This story, transmitted by the Associated Press, is a pool report by foreign correspondents in Liberia:

Rebels attacked an airfield that was Monrovia's last link to the outside world today and closed in on the city from two directions, in some of the heaviest fighting for control of the capital.

Rebel fighters under leader Charles Taylor resumed their offensive in the eastern part of the city, their latest in the country's seven-month civil war. Followers of a rival rebel commander, Prince Johnson, fought off government soldiers who tried to retake Bushrod Island in the north.

Acting Information Minister Paul Allen Wie told reporters that President Samuel Doe had no plans to step down, despite the advancing armies. "The president thinks it is worth dying for his country," Wie said.

A news release quoted Doe as saying a sudden resignation "would lead to greater anarchy and ethnic tragedy in Liberia."

Earlier today, government troops attacked two bridges that link the city center with rebel-held Bushrod Island, but they were pushed back by heavy gunfire.

State Department spokesman Richard Boucher said it appeared Johnson's rebel forces controlled the island, which includes Monrovia's port.

Johnson is believed to have split with Taylor sometime in the last three months, and some diplomats believe his army is now stronger than Taylor's National Patriotic Front.

A few miles east of Monrovia, rebels waded across a swamp and attacked Spriggs-Payne Airfield, the last way out of the city not under rebel control. It was not clear whether followers of Johnson or Taylor launched the airfield attack.

The rebels have accused Doe, who took power in a 1980 coup, of corruption, mismanagement and human-rights abuses. The United States has said its offer to provide safe passage out of the country for Doe stands.