Reports say 21 fighters have been killed in aerial strikes in the Tirah Valley in Pakistan's northwestern Khyber Agency.

The country's leaders pledged decisive action in the wake of Tuesday's school massacre in Peshawar, capital of Khyber Pakhtunkhwa province, which left 149 people dead, most of them children.

The massacre triggered international condemnation and led to calls in Pakistan for action against armed fighters.

Intelligence sources have told Al Jazeera that the mastermind of the school attack may himself have been killed in the airstrike, although this claim has not been independently verified. Omar Khalifa had claimed responsibility for the attacks in a video released online.

Saturday's bombardment comes a day after Pakistan hanged two convicted men in the first executions since 2008 after the government ended a moratorium on the death penalty in the wake of the school massacre.

Officials said that there may be 10 more executions in the coming days: six in Punjab province and four in southern Sindh province.

Meanwhile, US drone strikes in Data Khel area of North Waziristan province left five people dead on Saturday, Pakistani security officials said.

"A US drone fired two missiles at a compound in Mada Khail neighbourhood of Data Khel area in North Waziristan killing five militants. The death toll is expected to rise," a senior security official requesting anonymity told the AFP news agency.

Rebel strongholds

Also on Saturday, nine people including a policeman and a paramilitary soldier were killed in two separate incidents when security forces hit suspected rebel hideouts in the northwest, officials said.

In the first incident, police and paramilitary soldiers raided suspected hideouts in the Mechani neighbourhood of Shabqadar, a town around 30km north of Peshawar.

"A soldier of the Frontier Corps and a policeman embraced martyrdom in an exchange of fire with militants in Mechani neighbourhood of Shabqadar Saturday morning," local police official Wilayat Khan told AFP.

He said two fighters belonging to Tehreek-e-Taliban Pakistan (TTP), the group behind Tuesday's school massacre were also killed.

In the second incident, five members of the TTP including a local commander were killed officials said.

"Five members of the Tehreek-e-Taliban Pakistan (TTP) were killed in a raid on their hideout in Gujjar Gadi neighbourhood of Matni, around 16 miles (25km) south of Peshawar," a senior security official told AFP.

The Pakistani army has been waging a major offensive against longstanding Taliban and other rebel strongholds in the restive tribal areas on the Afghan border for the last six months.

Al Jazeera