One person was injured early Thursday in a grenade blast in an area of the northern city of Tripoli that has seen bloody clashes between two rival factions, a security official told Agence France Presse.

The grenade was thrown in the Jabal Mohsen and Bab al-Tabbaneh region where some 23 people were killed in June and July in battles between Sunni supporters of the government and their Damascus-backed rivals from the Alawite community in Tripoli.

Alawites are an offshoot of Shiite Islam.

Tensions between the two communities eased in the past few weeks after both sides signed a reconciliation accord and the army deployed heavily in the area.

But concern that the situation could escalate again mounted this week after a car bomb targeting the army on Monday left seven people dead, four of them soldiers, and at least 30 people injured.

No one has claimed responsibility for the attack.(AFP)