FREETOWN, Sierra Leone (AP) _ Helicopters clatter overhead. Armed U.N. soldiers keep a wary eye on passers-by at checkpoints and in front of key buildings. Small groups of people huddle anxiously around radios in the shade of trees or buildings to hear the latest news.

The tension is growing in this seaside capital. Sierra Leone's feared former rebel movement has taken some 300 U.N. personnel hostage, many more are missing, and at least four are presumed dead in clashes throughout Sierra Leone's interior.

Freetown, which has already lived through the horror of an assault by the rebel Revolutionary United Front, is wondering if it could soon be happening again.

The clashes, which began Monday as the West African intervention force that had helped bring an end to Sierra Leone's eight-year civil war was preparing for its final departure, have dealt a major blow to the nations' already fragile peace process.

The last soldiers from the Nigerian-led force known as ECOMOG left Sierra Leone on Tuesday. Many here believe that was a mistake, and gave the rebels _ who in principle are part of a power-sharing government created by a July peace accord _ free reign to savage the country again.

``The U.N. is a peacekeeping force, not a fighting force,'' said Muctarr Jalloh, whose right hand and ear were hacked off by the rebels during a systematic campaign of terror. But the rebels ``are not committed to the peace. It is only force that will take them out.''

At the camp for amputees where Jalloh now lives, people know too well what a rebel attack could mean.

``Those people are not human,'' said Nathaniel Beneh, gripping the stump that is all that remains of his right leg.

Many in this war-ravaged city cling to the desperate and unlikely hope that ECOMOG, who fought the rebels in hundreds of battles, will return.

``We are crying for ECOMOG because they know these people and they don't joke with them,'' said Lahai Tambawaty, a maintenance worker. ``When ECOMOG left some of those rebels were singing and dancing they were so happy.''

At a raucous meeting of parliamentarians and civil society leaders Friday, one speaker after another denounced the rebel attack and called for action, including a march to rebel leader Foday Sankoh's Freetown house to demonstrate the extent of popular outrage.

`If the RUF isn't stopped now ... this concept of reconciliation and forgiveness will die,'' said Charles Caulker, a member of Parliament's defense committee.

The biggest fear is that the United Nations _ the last protectors of the people of this troubled country _ may decide to pull out of Sierra Leone. U.N. officials are quick to say that no withdrawal of peacekeepers is planned, but acknowledged the peace has been violently jarred by the clashes and the hostage-takings.

``The basic premise of any peacekeeping mission is an agreement by parties in the conflict to the deployment of a neutral force to keep the peace,'' said UN spokesman Lt. Col. Jaswinder Sandhu. ``In this case, one of the major parties has backed out of the agreement and has gone and attacked that very peace force. The very basis of this mission is now in question,'' he said.

Richard Holbrooke, the U.S. envoy to the United Nations, warned in Kinshasa, the capital of Congo, another war-torn African nation, that the kidnappings and killings have stopped the U.N. force from being able to do its job.

``The situation in Sierra Leone is a lot more serious than the one here,'' he said. ``The peacekeepers (in Sierra Leone) must do their work and at the moment they cannot.''

But whether the violence will frighten the world body away from further peacekeeping missions in Africa _ where U.N. missions to countries like Somalia and Rwanda have already failed in recent years _ remains unclear.

The release Friday of the four member Russian crew and two civilians captured in the eastern city of Kailahun was the first bit of good news in days for this capital.

Here, Sankoh and his RUF officials have become common sights on the streets, just a little more than a year since the city last came under rebel assault.

Through the latest incidents, Sankoh has continued to deny his people holds any hostages. One rebel official suggested the U.N. staff were lost in the jungle and RUF soldiers were searching for them.

The people of Freetown, though, have long become accustomed to the strange and often-contradictory pronouncements of Sankoh and his lieutenants.

``These people turn like snakes,'' said Jalloh.