Pakistani security forces have freed two people taken hostage by anti-government fighters at an army intelligence office.

Forces stormed the office in Peshawar in the northwest of the country on Saturday forcing the hostage takers to surrender, Lisqat Ali Khan, a police official, said.

No fatalities were reported in the operation to rescue the captives, who were held after staff began moving three or four anti-government fighters in the office.

"When they were being shifted from one compound to another, all of a sudden they grabbed guns from one of the guards and opened fire" and took two people hostage, Khan said.

Missile strike

Separately, at least four people were killed in a suspected US missile strike in the northwest, intelligence officials said on Saturday.

The officials, who spoke on condition of anonymity, said the strike targeted suspected anti-government fighters in vehicles travelling in the Kurram tribal region.

The identity of those killed was not immediately clear.

"There were attacks in three different places on Friday evening," the Reuters news agency quoted one government official in the region as saying.

The attack, like others in northwest Pakistan, was believed to have targeted the Haqqani Network,which is considered by the US to be the greatest threat to Nato forces in eastern Afghanistan.

However, the US government does not acknowledge such missile strikes, which are reportedly run by the Central Intelligence Agency (CIA).

Pakistan is a US ally in the war against Taliban and al-Qaeda fighters, but it has voiced resentment over such pilotless aircraft attacks.

Islamabad considers remote-controlled attacks, which have angered civilians in the country's tribal regions, a breach to its sovereignty.