Khan said the operation took place overnight in the Tirah valley of Khyber, one of Pakistan's seven semi-autonomous tribal areas through which flows the bulk of supplies destined for US-led and Nato troops in Afghanistan.
Mistri Gul, a spokesman for Lashkar-e-Islam, said: "Eight of our members were killed.
"We don't know about the rest, they might be civilians."
Pakistani authorities accuse Lashkar-e-Islam of kidnapping for ransom in Peshawar and running torture centres and private jails.
Pakistan government troops are locked in battles against fighters in parts of Pakistan's northwest where US officials have said al-Qaeda and Taliban-linked fighters are present.
Pakistan poured paramilitary troops into Khyber in June last year to counter fighters threatening to take over Peshawar in the northwest, and to stop attacks on convoys supplying Western troops based in Afghanistan.
On the outskirts of Peshawar, a remote-controlled bomb ripped through a police patrol on Thursday, killing at least two policemen, Safwat Ghayur, the city police chief, said.
There was no immediate claim of responsibility for the attack.
Many of the most recent bombings in northwest Pakistan have been seen as attempts by Taliban fighters to avenge a two-month military offensive against the Taliban in three northwest districts that has been welcomed by the United States.