Seven persons were killed and over 10 injured in sectarian clashes in Pakistan's northwestern Kurram tribal area, where skirmishes between Shias and Sunnis continued for the second day on Thursday.

Security forces used artillery to target trenches occupied by the two groups in two areas in upper Kurram Agency. Both groups are using automatic and heavy weapons like mortars to attack each other's positions.

The local political administration said three persons were killed when clashes broke out between the Shia Turi and Sunni Mengal tribes. Four more persons were killed today, Dawn News channel reported.

The situation in the area is tense and the road linking Parachinar, the main town of Kurram Agency, to other areas is blocked, causing shortage of food and medicines.

Hundreds of people have been killed in sectarian clashes across Kurram Agency since October last year despite a peace agreement finalised by a tribal jirga.

Meanwhile, 35 prisoners escaped from a jail in lower Kurram this morning. The prisoners who were agitating pushed fled after overpowering guards.

Assistant Political Agent Ataur Rehman said most of the prisoners who escaped were serving sentences for petty crimes. Only four were murderers, he said.

Police are conducting raids to nab the escaped prisoners, he said.