Liberian Rebels Gain; U.S. Forces Poised : Africa: Americans are urged to leave, and six warships and 2,000 Marines stand by for rescues if needed.

Rebel troops advanced to within 25 miles of the capital Thursday, and the Pentagon announced that a U.S. navy flotilla with more than 2,000 Marines is off Liberia in case American citizens need to be evacuated.

Liberian President Samuel K. Doe refused to resign despite the advance of the insurgents, and he vowed to be the last person to leave the city.

“Tough times never last. Tough people do,” Doe told a group of foreign ambassadors, according to one envoy at the meeting.

His statements heightened fears of a bloody conflict if the two armies clash in the West African capital. So far, more than 1,000 people have been killed in the five-month rebellion, most of them civilians slain by government troops.

Late Thursday, the State Department warned in a travel advisory that conditions in the country are deteriorating and ordered all non-essential U.S. personnel to depart immediately.

Cmdr. David Thomas, a spokesman for the Defense Department, said the U.S. flotilla includes a destroyer, an amphibious assault ship, a tank-landing ship and other support vessels carrying ammunition and combat supplies.

Aboard the ships are 179 Marine officers and 2,102 enlisted men, Thomas said.

He said the U.S. ships are under orders to “be prepared to evacuate American citizens in the event that they would no longer be able to leave the country by commercial means.”

About 1,100 Americans, mostly businessmen and missionaries, remain in Liberia, the State Department said late Thursday. About 5,000 U.S. citizens were reported in Liberia in May but many have left since the unrest worsened, U.S. officials said.

Doe spoke with diplomats who protested an attack on a U.N. compound Wednesday by soldiers carrying out reprisals against unarmed civilians.

According to ambassadors at the meeting, Doe promised to send troops to protect diplomatic missions. But one envoy said they are trying to find a diplomatic way to refuse the offer.

“The last thing we want is unruly armed Doe soldiers. We would rather have policemen,” said the diplomat, who spoke on condition of anonymity.

Doe was defiant during the meeting, despite a promise he made to a rally Friday that he would make any sacrifice, including stepping down, if it helped end bloodshed.

“He said he would not resign but would be the last person to leave,” the diplomat said. Rebel leader Charles Taylor said Thursday in an interview with the British Broadcasting Corp. that he would not be satisfied with Doe’s resignation. The rebels have accused Doe’s administration of corruption, economic mismanagement and human rights abuses.

Taylor, who said he was calling the BBC from the port of Buchanan, said his fighters will not stop until they have taken Monrovia and formed their own government. Taylor’s fighters captured the country’s main port of Buchanan, 95 miles southeast of the capital, five days ago.

Rebels were reported to be ambushing troops within a few miles of the main Robertsfield International Airport, 20 miles from the capital.

Doe seized power as a master sergeant in a bloody 1980 coup that ousted elitist descendants of slaves who discriminated against native Liberians. Liberia, a country of 2 million, was founded by freed American slaves in 1847.

Doe and his officers are members of the Krahn tribe, which is only 2% of the population in this nation of 14 small tribes.

The rebels are chiefly Gio and Mano tribesmen, although Taylor had an American-Liberian father and a Bassa mother.

The rebellion began Dec. 24 with an invasion of 200 rebels from Ivory Coast.