Forces loyal to one of the Liberian rebel factions seized 14 or 15 foreigners, including one American, as hostages yesterday, taking them from a Monrovia hotel to a rebel headquarters outside the capital city, U.S. officials reported.

State Department spokesman Margaret Tutwiler declined to give the name of the American seized. She said that as far as she knew, none of the hostages had been harmed.

Meanwhile yesterday, five West African countries agreed in principle to a possible military intervention to stop the bloody civil war, according to a wire service report from Gambia, where the leaders were meeting.

The hostages were seized by rebel members of a faction headed by Prince Johnson, who on Saturday threatened to arrest all foreigners in order to provoke international intervention in the country's civil war, which has claimed the lives of 5,000 people, mostly civilians.

Johnson, leader of one of two competing groups attempting to topple President Samuel K. Doe, said he would target American, British, Lebanese and Indian civilians.

His threats prompted President Bush to send in 255 Marines Sunday to secure the U.S. Embassy and to remove 62 Americans, including 21 who were working at two transmitter sites near Monrovia. Officials said the United States does not intend to intervene on anyone's side in the conflict.

Tutwiler said another 20 people, including six U.S. employees, were airlifted out of the capital yesterday, bringing to 94 the number of people, including several of other nationalities, who have been ferried out since the Marines landed Sunday. The evacuees were taken to Sierra Leone and about 35 have already left there en route to the United States, she said.

There are about 39 American officials at the embassy, Tutwiler said, adding she did not know how many other Americans might be on the grounds. More than 230 Marines remained dug in around the embassy.

"Monrovia remains relatively quiet," she said, "with only sporadic fighting. All major stores remain closed. There is no public water, electricity or phone service . . . food shortages are intensifying."

As many as 500 U.S. citizens remained voluntarily in the country. Many of them have dual citizenship and are not expected to leave.

The leaders of Nigeria, Sierra Leone, Guinea, Ghana and Gambia agreed in principle that they would send troops and a naval task force to Liberia to help end the seven-month-old war that one leader said had turned the country into a "slaughterhouse."

The Associated Press, quoting sources attending a meeting of the West African Economic Community, said that the leaders were considering intervening to impose a cease-fire, install an interim government and hold elections.