Up to four suspected militants were killed in US drone strike which fired four missiles targeting a vehicle and a house in Dattakhel area of North Waziristan Agency (NWA) on Monday.

Official sources said that a vehicle and a house were targeted by the US drone which fired four missiles, killing four people and leaving one injured.

The vehicle was destroyed completely in the strike while house in which female and children were also present was partially damaged in the attack. It was also reported that women and children remained safe in the attack. However, media had to rely on one side of the story because it has no access to the area to get independent reports.

It was also not yet clear that any high value target was either killed in the attack or innocent people fell prey to the US covert operation which was halted for eight weeks following tensions in the US-Pak relations over the Nato forces attack in the bordering area, killing 24 Pakistani soldiers.

However, on condition of anonymity, a Pakistani official told foreign media earlier that he runs a network of spotters primarily in North and South Waziristan, described for the first time how cooperation on strikes works, with his agents keeping close tabs on suspected militants and building a pattern of their movements and associations.

The official said that we run human intelligence network and separately we monitor cell and satellite phones of the militants in the rugged region.

The official revealed that joint monitoring operations are being run with Pakistan's US and UK friends, adding that cooperation with British intelligence was also extensive.

Pakistani and US intelligence officers, using their own sources, hash out a joint "priority of targets lists" in regular face-to-face meetings, he said.

The official said that once a target is identified and "marked," his network coordinates with drone operators on the US side. He said the United States bases drones outside Kabul, likely at Bagram airfield.

From spotting to firing a missile "hardly takes about two to three hours", the official said.