Hundreds of tribal police in the northwestern Khyber region have quit their jobs because of militant threats, even as Pakistani forces reported killing 22 insurgents in an ongoing military operation there, officials said Saturday.

Pakistan is under intense U.S. pressure to crack down on Al Qaeda and Taliban militants along the Afghan border. Khyber is of particular concern because militants there frequently attack trucks carrying supplies destined for U.S. troops in Afghanistan.

Pakistan began its latest offensive in the Khyber tribal region on Sept. 1 and says it has killed over 150 militants. The fighting has caused thousands of residents to flee.

Paramilitary troops Saturday destroyed three militant hide-outs and killed 22 insurgents, the Frontier Corps said in a brief statement. It is impossible to verify accounts of fighting there because the army is blocking roads into the region.

One of the key targets of the operation is the Taliban-affiliated group, Lashkar-e-Islam.

Some 350 tribal police in Khyber quit their posts after the chief of Lashkar-e-Islam made a radio broadcast telling all government officials to resign in protest over the military operation, said local government official, Fazal Mahmood.

Tariq Hayat, the top government official in the area, said the men would be fired.

"I would presume that their loyalty lies with (the militants) rather than with the state," he told the ExpressNews TV network. "We are terminating those people. The orders are being issued just now."

The army is fighting militants in various parts of the northwest. On Friday, it announced the capture of five top Taliban commanders from the Swat Valley, including spokesman Muslim Khan.