NAHR AL-BARED (Lebanon), May 21: Lebanese troops bombarded Islamist militiamen with tank shells and heavy artillery on Monday, the second day of the bloodiest internal fighting since the civil war that has now left 55 people dead and raised fears about Lebanon's fragile security.

Nine civilians were killed in heavy shelling of a Palestinian refugee camp in northern Lebanon, besieged by soldiers in tanks who are battling militants from the shadowy Sunni group Fatah al-Islam, a camp medic said.

Huge plumes of thick black smoke billowed into the sky over the Nahr al-Bared camp, which has been turned into a war zone by ferocious gunbattles between soldiers and Fatah al-Islam, a group accused of links to Al Qaeda and Syrian intelligence services.

Fears were mounting of a humanitarian crisis in the camp, a coastal shantytown of narrow alleyways where rescue workers were struggling to evacuate the dead and wounded and buildings were bombed out and power supplies cut.

The international community condemned the violence and voiced support for the Lebanese government's efforts to restore order after 46 people were killed on Sunday alone.

As warships patrolled nearby coastal waters, troops were locked in heavy exchanges of artillery and machinegun fire and a military spokesman said the army had extended its control to all camp entrances.

But Fatah al-Islam threatened to extend attacks beyond Tripoli if the army continues to pound its positions.

“The army is not only opening fire on us. It is shelling blindly. If this continues, we will carry the battle outside the city of Tripoli,” spokesman Abu Salim Taha said.

Officials voiced fears about the plight of refugees trapped in the camp, where the Red Cross was able to evacuate about 17 people during a brief lull in the fighting.

“We are deeply concerned about the developing humanitarian crisis, particularly the danger to civilian lives,” UN Palestinian refugee agency director Richard Cook said.

Doctors described seeing bodies strewn on the streets of Nahr al-Bared, which like all refugee camps in Lebanon remain outside the control of the government and in the hands of Palestinian factions.

“The electricity has been cut, there's not much water and the camp's bakeries are shut,” said Hajj Rifaat, an official from the mainstream Palestinian movement Fatah.

It is the worst explosion of violence -- excluding warfare with Israel -- since the 1975-1990 civil war and has raised fears about the stability of multi-confessional Lebanon, already in the grip of an acute political crisis.

A 63-year-old woman was also killed and 10 people wounded in a bomb blast in a Christian area of Beirut on Sunday.

The gunbattles erupted at dawn on Sunday after Fatah al-Islam ambushed an army post outside the camp, and spread to Lebanon's second city of Tripoli where troops staging an assault on a building where fighters were holed up.

That day, 27 soldiers and 17 gunmen were reported killed, in addition to a civilian and a refugee in Nahr al-Bared, home to about 30,000 of Lebanon's estimated 400,000 Palestinian refugees.

A security official said government forces found the bodies of 10 Islamists, including Saddam Hajj Dib who was wanted over a plot to blow up trains in Germany last July, in the building stormed on Sunday.

Another was identified as Abu Yazan, Fatah Al-Islam's number three, accused of responsibility for bus bombings in February that killed three people.—AFP