BEIRUT: Lebanese troops deployed in Sunni areas of the capital on Monday as fresh sectarian violence erupted, stoking stability fears after a top security official was killed in a bombing blamed on neighbouring Syria.

The army said it was determined to restore order, with the northern port of Tripoli also shaken by fighting between partisans and opponents of Syrian President Bashar al-Assad that killed seven people.

In the afternoon, personnel carriers entered Beirut's Sunni district of Tariq Jdideh, which had been a hotspot all day, and soldiers took up position on streets leading into it to keep them open, a military spokesman said.

Six people were wounded when the army made a pre-dawn sweep of Tariq Jdideh in pursuit of armed men, and automatic weapons and anti-tank rocket fire could be heard.

Later, soldiers responded after being fired on as they tried to clear a road into the district, a stronghold of opposition leader Saad Hariri whose supporters had blocked it despite calls by the former premier to stay off the streets.

The army spokesman said a 20-year-old Palestinian, Ahmad Quaider, was shot after firing at an army patrol.

In Tripoli, a Sunni bastion where opposition to Assad is strong, seven people were killed and 12 wounded during clashes between Sunnis and Alawites, an offshoot of Shia Islam to which the Syrian president belongs, security sources said.

Two Alawites and five Sunnis died. The same sources reported snipers in the city late on Monday.

Clashes have erupted regularly in Tripoli as tensions spill over the border from Syria, where a 19-month-old anti-regime revolt has left more than 34,000 people dead.

Lebanon has been on edge since Friday, when police intelligence chief General Wissam al-Hassan died in the Beirut bombing.

The attack sparked immediate calls for Prime Minister Najib Mikati, whose cabinet is dominated by Damascus ally Hezbollah, to resign.

Hezbollah's militia, which never disarmed after the 1975-90 civil war, is the most powerful military force in Lebanon.

A statement from the army high command said it is “committed to its role of stopping security breaches and maintaining civil order.

“Recent developments prove decidedly that the country is going through a critical time, and the level of tension in some areas has reached unprecedented levels,” it said.

It will take “resolute measures, particularly in areas of mounting sectarian friction... to prevent the assassination of martyred General Wissam al-Hassan from being exploited as an opportunity to murder the nation as a whole.”

The military also appealed to all political forces to be wary of their words and any calls for mobilisation, “because the fate of the nation is at stake.”