The raids in which militants loyal to Maulvi Fazlullah took part have left about 100 members of Pakistan's security forces dead, angering the military which faces threats from multiple militant groups.

"The problem refuses to go away," Pakistani army spokesman, Major-General Athar Abbas, told Reuters.

Fazlullah was the Taliban leader in Swat Valley, about 100 miles northwest of Islamabad, before a 2009 army offensive forced him to flee.

Fazlullah, who was also known as FM Mullah or Radio Mullah for his fiery radio broadcasts, managed to regroup in Afghanistan and establish strongholds and local support, and poses a threat to Pakistan once again, said Abbas.

"Now Fazlullah and his group are trying to re-enter Swat through Dir," said Abbas.