Military and U.N. transports drop off supplies and pick up evacuees at Freetown's airport

FREETOWN, Sierra Leone (CNN) -- There was intermittent fighting Saturday in and near Freetown, where rebels have warned the Sierra Leone government that its capital could come under renewed attack within 24 hours.

Tense soldiers patrolled the near-empty streets of Freetown's west end, while artillery rounds crashed into rebel positions in the hills to the south.

Rebel commander Sam Bockarie called for an offensive against the city Friday, despite a weeklong cease-fire proposed by jailed rebel leader Foday Sankoh and Sierra Leone President Ahmad Tejan Kabbah.

On Saturday, street fighting was reported near one of Freetown's main military bases, the Wilberforce Barracks. Bockarie, field commander of the Revolutionary United Front (RUF), had also pledged to press his offensive against the Lungi International Airport complex, where Kabbah has taken refuge.

Government troops and the Nigerian-led West African coalition force (ECOMOG) worked through the night carrying in supplies and evacuating refugees from the threatened districts on the city's west side.

"We've taken up defensive positions and are holding our ground," said a district government-allied commander who spoke on condition of anonymity.

Rebels demand ouster of president

Forces loyal to Kabbah patrol the Lungi International Airport near Freetown, Sierra Leone

Rebels fought their way into Freetown's Eastland district Wednesday, and were reported to be using civilians as shields to slow down government counterattacks. On Saturday morning, smoke poured from the rebel-held sections of the city.

U.N. special representative Francis Okello said Friday he was optimistic the cease-fire would hold, despite the sporadic fighting.

"It is not surprising to have some clashes in the early stage of a cease-fire," he said.

The RUF has demanded Kabbah's ouster and the release of Sankoh, but have given no other demands for their latest campaign to take the West African country's capital. Sankoh was convicted of treason and sentenced to death for recruiting the band of rebels, who have waged a deadly campaign against the government for years.

Ivory Coast brokered a brief cease-fire between the government and rebel troops in 1996. Kabbah, who was elected president in 1996, was deposed in 1997 by a military junta allied with the rebels. ECOMOG restored him to power 10 months ago.

Responding to the latest round of fighting, former colonial power Great Britain said Saturday it was sending a warship into the region "as a precautionary measure." The frigate Norfolk is expected to be in the area next week, and will monitor developments there.

"It's a straightforward precautionary measure to give us a ship available in that part of the world," said a British Defense Ministry spokesman on condition of anonymity. "No decision has been taken yet on what, if anything, to use the Norfolk for."

Reuters contributed to this report.