This offensive includes raids on the rebel headquarters in Voinjama, on the border with Guinea, which Liberia accuses of backing the Liberians United for Reconciliation and Democracy (Lurd) group.

Fierce fighting is taking place in the town of Zorzor and Voinjama in northern Liberia and Bopolu and Tubmanburg in the north-west

Lieutenant-Colonel Richard Bannah

Last month, rebel forces came to within 25 kilometres of the capital, Monrovia, but government troops have since pushed them back.

A high level military delegation from the Economic Community of West African States (Ecowas) was due in Liberia on Friday to assess the military situation resulting from the ongoing fighting.

The BBC's Jonathan Paye-Layleh in Monrovia says the mission's findings are likely to lead to a ceasefire between the two warring sides.

Political observers in the capital see the latest all-out counter attacks by government as an attempt to deny the rebels control of territory in the event of any ceasefire.

The government has previously ruled out a ceasefire with the rebels.

No ammo

"As we speak, fierce fighting is taking place in the town of Zorzor and Voinjama in northern Liberia and Bopolu and Tubmanburg in the north-west," army spokesman Lieutenant-Colonel Richard Bannah said.

President Charles Taylor has said that a United Nations arms embargo has prevented his forces from defeating the rebels.

The sanctions were imposed for Mr Taylor's support for rebels in the civil war in neighbouring Sierra Leone.

Well-placed defence sources have told our correspondent that the town of Bopolu changed hands at least twice within the past two days.

The government army's mission to retake the town was thwarted when they ran out of ammunition, the sources said.

Rebel forces who had abandoned the town briefly re-organised, split into two groups and retook the town.

Ambush

But reports say on that same day, a pick-up truck, loaded with rebel reinforcements heading for Bopolu from the embattled provincial town of Tubmanburg was ambushed by government troops.

An unspecified number of the rebels were reportedly killed, and several government soldiers were injured by return gunfire.

President Taylor may now agree to a ceasefire

Defense Minister Daniel Chea, who has just returned from the Guinean capital discussing the Liberian crisis with the military authorities of that neighbouring country, confirmed the military hostilities around Bopolu.

The fighting in recent days has rendered the highway between Bopolu and Tubmanburg so volatile that both government and rebel troops now feel unsafe driving through it.

There are also reports of acts of arson against residential buildings in the Coleman Hill suburb of Tubmanburg, which has seen some of the toughest fighting for control of the old iron ore mining town.