At least one person has been been killed and 20 others wounded by a powerful blast in the northern Lebanese city of Tripoli, officials said.

The blast early on Saturday struck a six-storey residential building in the Sunni neighbourhood of Bab al-Tebbaneh.

The Associated Press news agency, citing an anonymous official, reported the explosion was caused by a bomb placed in the first floor of the building.

Police and army troops were deployed to the area, although there were no reports of fighting.

The neighbourhood was the scene of fierce clashes last week between pro- and anti-government fighters.

Rescue workers helped pull victims from the rubble and get them to hospital.

Shops on the ground floor of the building and four apartments on its first floor, were destroyed by the blast.

Cars on the street were also damaged.