Liberian rebels are approaching Monrovia's city center in an offensive that started Tuesday, while President Charles Taylor vows to fight on. Rebels firing rockets and mortars have crossed at least one bridge leading to the center of the capital, Monrovia.

Fierce fighting between the rebels and forces loyal to Mr. Taylor has also taken place in the western port area of the capital.

Monrovia resident Boyzuway Zay Zay said he is bracing for all-out fighting in the city center.

"We can hear the small arms under the artillery," he said. "We have never heard that before during the past war. So from our end now we can hear the small arms so definitely we expect a worse situation."

Rebels, who want Mr. Taylor's immediate resignation, control most of Liberia, but have never been able to capture the capital in their four-year insurgency.

Another Monrovia resident, who identified himself as Frankie, says thousands of civilians are fleeing the offensive, hoping the international community will intervene to stop the fighting.

"It's just total confusion and chaos," he described. "Civilians have been leaving Monrovia today in droves. People in Monrovia remain hopeful that there will be some sort of intervention from the international community. The situation has passed the critical stage. It's more than critical. People are dying here by the minute."

Earlier Wednesday, Mr. Taylor spoke on Liberian radio, vowing to fight to the end to defeat what he called a wave of terror.

The government and envoys for two rebel groups signed a ceasefire agreement in Ghana last week, but Mr. Taylor later said he would refuse to step down before his term expires in January, as stipulated in the accord.

Mr. Taylor has also said peace talks will fail if a United Nations-backed court in Sierra Leone does not lift an indictment against him for war crimes.

Mr. Taylor, himself a former rebel, has been accused of fueling instability throughout west Africa by smuggling weapons, diamonds and timber, charges he denies.