An explosion rocked Beirut, wounding 10 people, as deadly clashes engulfed the Lebanese army and Muslim extremists in the southern and northern parts of the country.
The bus bombing late on Monday in the capital raised the state of chaos in the country and opened new fronts for the army as it continued to battle an Al Qaeda-inspired militia in a 16-day standoff in the Nahr al-Bared Paletinian refugee camp in the north of the country.
Beirut residents were plunged in panic when a huge blast was heard in the Christian area of Sud al-Bouchariyeh. The explosion on an empty bus left 10 wounded, and there were no fatalities.
The new violence in the capital came as Lebanese troops resumed their shelling on Fatah al-Islam gunmen holed up in the Nahr al-Bared camp near the northern port city of Tripoli in a standoff that has left more than 107 people dead.
The latest flare-up has raised concerns that the violence could spread to more of the 12 camps, which are the home of some 367,000 Palestinian refugees in Lebanon.
Earlier, residents in the outskirts of the southern port city of Sidon, about 30 km south of Beirut, expressed concern as gunbattles between the Lebanese army and Sunni Muslim extremists flared late on Sunday near Ain al-Hilweh, the largest of Lebanon's 12 refugee camps in Sidon.
Two soldiers and two militants were killed and 11 wounded, a military spokesman said, and dozens of families fled to safety before calm was restored later Monday.
The violence in Ain al-Hilweh was contained after Muslim clergymen and members of the mainstream Fatah Movement intervened and the army deployed more armoured vehicles and boosted security in Sidon. Schools were closed and many shops remained shut in the area.
The fighting pitted troops against gunmen from Jund al-Sham (Soldiers of Damascus), a little known group mainly made up of Islamist Lebanese extremists, most of whom are wanted by the Lebanese authorities.
The explosion in the mixed residential and industrial district was the fourth to rock Lebanon since clashes between the army and the Islamists broke out on May 20.
Meanwhile, Washington has announced that it was considering sending more supplies to help the Lebanese army in their fight against extremists. Congress raised the amount set aside for military assistance to Lebanon to $280 million in 2007.