"According to reports received by us, commander Alamgir has been  killed in the air strike and several other casualties are likely because ammunition at their hideout exploded," the official told told the AFP news agency.

"It was a militant den. We cannot confirm casualties immediately."

The official said that intelligence reports had indicated a large fighters' gathering in the area, a stronghold of extremists loyal to Fazlullah, who has declared a holy war against the  government.

Friday's air strike

Pakistani security officials had earlier said that air strikes killed 60 pro-Taliban fighters and destroyed a training camp in the same area on Friday.

Swat valley was until last year a popular tourist destination where many Pakistani city dwellers went for their annual holidays and it featured Pakistan's only ski resort.

But the region has been turned into a battleground since Fazlullah launched an armed campaign to enforce Sharia law.

In other violence, Pakistani fighter jets and helicopter gunships struck fighters' positions in Bajaur, a mainly ethnic Pashtun region near the Afghan border, but there were no immediate reports of any casualties.

The military said it has killed about 1,100 fighters in clashes in Bajaur since August but there has been no independent verification of that casualty estimate, or of estimates for casualties in Swat.

Meanwhile in Dera Bugti, a town in Baluchistan province, a roadside bomb struck a vehicle carrying an ethnic Baluch tribal politician, killing three of his guards and wounding five others.

The politician, a supporter of former President Pervez Musharraf, was not injured.