MONROVIA, LIBERIA, JULY 26 -- This story, transmitted by the Associated Press, is a pool report by foreign correspondents in Monrovia:

Government troops rounded up civilians suspected of supporting the rebellion against the government and executed them, as the rebels tightened their grip on the capital, witnesses and diplomats said today.

Ambassadors of five European Community nations represented in Liberia -- France, Britain, Italy, Germany and Spain -- expressed in a public statement "horror and disgust at the tribal killings of innocent civilians being carried out by both sides in the present conflict."

The rebels could be seen trying to battle their way over a bridge into the center of the capital, where a defiant President Samuel Doe remains barricaded in his mansion.

In Washington, State Department spokesman Richard Boucher said Doe still has not asked the United States for help it has offered him in leaving his country, most of which is held by rebels.

The spokesman said insurgent troops, believed to be those of rebel leader Charles Taylor, moved into the city this morning after heavy fighting northeast of the capital on Wednesday night.

Other rebel forces, presumably those of a rival rebel leader, Prince Johnson, also entered Monrovia amid small-arms fire, Boucher said.

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

The rebels, who began their offensive under Taylor in December, accuse the government of corruption and human-rights abuses.

Soldiers of Doe's Krahn tribe killed at least two dozen civilians who were taken from their houses, from a hospital ward and from lodgings near the beleaguered city's one remaining airstrip, said the witnesses and diplomats, who spoke on condition of anonymity.

The civilians, some of whom were shot while tied back to back with their hands bound behind them, were Gio or Mano tribesmen suspected of supporting the rebels.

Some victims were taken overnight to a beach near the city's exclusive Mamba Point district where they were shot or slashed to death with machetes, the witnesses said.

The victims' bodies and the rotting remains of previous victims were dumped into the sea nearby and could be seen bobbing in the surf, the witnesses reported.

The Western European ambassadors' statement said there was "ample evidence that government soldiers are continuing to murder {noncombatant} Gios and Manos . . . while the National Patriotic Front are murdering Krahn and Mandingos."

The ambassadors reiterated an earlier appeal for restraint on both sides. "If Liberia as a nation is to retain the respect of the rest of the world, these killings must cease forthwith," they said.

More than 8,000 refugees were camped without food or water in a U.S. compound near the American Embassy, and many reacted with terror when security guards passed word that soldiers intended to enter to check identities and search for rebels.

A hushed silence fell on the camp as soldiers arrived at the perimeter, but they searched only a few people outside and did not enter the compound.

The U.S. Embassy has provided a few medical kits and the services of an embassy physician but has been unable to supply the refugees with food and water.

About two dozen soldiers blocked the path of three foreign reporters covering the conflict and seized their car without explanation. Some ordered the reporters to leave the city center.

"It is not safe. There is nobody in control here," one soldier said.

Discipline among the estimated 1,500 remaining troops loyal to Doe has broken down, and a Western diplomat said many were drugged.

But some diplomats also had discounted Doe's troops more than a month ago, predicting they would flee as soon as rebels got anywhere near the city.

Some government units have continued to fight, blocking Taylor's main rebel force in the city's eastern suburbs.