Updated

Philippine Vice President Jejomar Binay is to travel to the southern city of Zamboanga on Saturday in a bid to broker a truce with Muslim rebels holding scores of civilian hostages while locked in a deadly stand-off with government forces.

A spokesman for the vice-president said Binay had talked to the leader of the rebels in the port city after five days of heavy fighting that have left 52 people dead and 70 wounded and had proposed a ceasefire that would come into effect at midnight on Saturday.

"He (Binay) talked to (rebel leader Nur) Misuari and he talked to (Defence Secretary Voltaire) Gazmin, and they agreed to discuss a ceasefire," the vice president's spokesman Joey Salgado told AFP early Saturday.

Salgado said the vice president would visit Zamboanga to discuss the details of his plan with the defence secretary and representatives of the Moro National Liberation Front (MNLF).

Some Philippine newspapers and radio stations reported that the truce was to have taken effect as early as midnight Friday but there was no sign of a ceasefire in the city of nearly one million people on Saturday.

Local officials said Binay had not yet arrived.

Defence Secretary Gazmin, who is in Zamboanga, said security forces were continuing efforts to free the hostages held by the MNLF in several coastal districts, where they have also set fire to many homes.

During an interview with ABS-CBN television he insisted that any truce was dependent on a ceasefire from the rebels, who "are firing as we speak".

Misuari's MNLF had waged a 25-year guerrilla war for independence in the country's south before signing a peace treaty in 1996 that granted the Muslim minority limited self-rule.

He disappeared from public view when the MNLF launched the attack on Zamboanga on Monday and has accused the government of violating the terms of the 1996 treaty by negotiating a separate peace deal with a rival faction.

That faction, the Moro Islamic Liberation Front (MILF), is in the final stages of peace talks with Manila and is expected to take over an expanded autonomous Muslim region in the south by 2016.

President Benigno Aquino, who visited Zamboanga on Friday, said the talks aim to end decades of rebellion that had claimed 150,000 lives in the country's Muslim southern regions.

Armed forces spokesman Lieutenant-General Ramon Zagala told AFP that gunfights were continuing in several districts of Zamboanga city early Saturday.

"As of now we have no ceasefire," he said.

"We continue to conduct offensives to prevent them from further endangering the lives of the civilian population and destroying property."

He said the rebels had suffered 43 fatalities and 19 others had surrendered or been captured, meaning they have lost about a third of the estimated 180 gunmen who infiltrated six coastal districts of Zamboanga early Monday.

Five soldiers and policemen and four civilians have also been killed, while 46 members of the security forces and 24 civilians had been wounded, Zagala said.

Local officials said 24,000 people have fled their homes.

About 3,000 elite troops are now advancing on MNLF positions, Zagala said, describing the military's gains as "substantial" while refusing to say which areas had been retaken by security forces.

"To stop the destruction we have to move forward. After that we don't move back," he said.