The Lebanese army said it has detained a man suspected of beating and shooting Alawites in the northern city of Tripoli, scene of frequent violence linked to the Syrian war.

Most Sunni Muslims in Tripoli, Lebanon's second largest city, support the revolt against Syria's President Bashar al-Assad, who belongs to the Alawite offshoot of Shiite Islam.

On Saturday assailants ambushed a bus transporting workers from Beirut to Tripoli as it made a routine stop at the entrance to Bab al-Tebbaneh district.

They forced nine of them off the bus and pushed them into the Sunni-populated neighbourhood before opening fire on them and beating them.

The nine were all wounded, but none critically.

In a statement issued late Saturday, the army said it had detained one suspected assailant and identified other men involved in the attack, including a Syrian.

"As a result of a search and our investigations, we have identified the armed men and all those involved in the shooting operation," said the statement.

"Army units raided their hideouts and detained Yehia Samir Mohammed... and are working on chasing down the other suspects," it added.

Tripoli is the scene of frequent Syria-linked battles pitting Sunnis from Bab al-Tebbaneh against Alawites in neighbouring Jabal Mohsen.

The latest, week-long battle killed 15 people on both sides and ended earlier this week when the army deployed along Syria Street, which separates the two districts and acts as the makeshift frontline.