Miranshah (NWFP), Oct 1: In another incident of the likes which have heightened tensions between America and Pakistan over the past one month, four tribesmen were killed and nine others injured, when a missile was launched by a suspected US spy drone.

The attack is the latest in a string of incidents on the rugged NWFP that have strained Pak-US ties, including a clash between Pakistani troops and US-led forces in Afghanistan.

Wednesday’s incident happened shortly after Pashtun tribesmen shot at three drones circling the village of Khusali Toorikhel in North Waziristan, a known hideout of Taliban and Al-Qaeda militants.

“After the drones came under fire a missile hit a house in the village. We have four dead now and another nine people were injured,” The News quoted a local security official as saying.

The US has stepped up attacks on militants in Pakistani territory since a new civilian government came to power in March and the incidents have become an issue in the US presidential election.

Washington had on Monday said that it supported Pakistan''s "territorial integrity" amid the tensions between the two allies in the "war on terror". The US government presented the stand in a joint statement with Pakistan following talks in Washington between US Deputy Secretary of State John Negroponte and Pakistan''s Foreign Minister Shah Mehmood Qureshi. (ANI)