At least 20 armed supporters of a pro-Taliban cleric were killed Thursday as gunship helicopters and artillery pounded their positions in Pakistan's north-west Swat valley, the military said.

"Today gunship helicopters targeted militant positions north of Kabal and Kuza Bande," a statement released on the website of the army's Inter Services Public Relations said.

"In both these actions, local sources and militant communication intercept reports have confirmed that eight militants were killed and their ammunition dump and mortar positions were destroyed," it added.

In another incident, the military launched an attack against the rebels in Alpurai town, which was seized by the extremists on Tuesday, with artillery and mortar fire. At least 12 militants were killed in the action.

Meanwhile, there were also unconfirmed reports of civilian casualties in the local media.

At least 14 people died Thursday when a mortar shell fired by the Pakistan army hit a house in Shangla area, Aaj news channel said.

The actions came a day after 35 people - 33 militants and two soldiers - were killed in the clashes between the government forces and the rebels.

Islamabad sent additional troops to the region in late October to put down the rebellion instigated by radicle cleric Maulana Fazlullah for the enforcement of Taliban rule.

Scores of people, including dozens of soldiers, have died in more than two weeks of violence.