DERA ISMAIL KHAN, Pakistan (Reuters) -- Suspected U.S. drones have fired at least two missiles into Pakistan's South Waziristan region on the Afghan border, killing seven people, intelligence agency officials and residents said.
U.S. forces in Afghanistan, frustrated by a spreading Taliban insurgency that is getting support from militant enclaves in northwest Pakistan, have stepped up strikes by pilotless drones despite Pakistani objections.
One missile hit a vehicle in a village near Wana, the main town in the region, killing four people, while three were killed in another strike in a nearby village, two Pakistani intelligence agency officials said.
"Tribesmen opened fire on the drones after the attacks," a Wana resident told Reuters by telephone.
The vehicle targeted in one attack was fitted with an antiaircraft gun and the militants fired shots at the drone before the missile hit it, one of the intelligence officials said.
The identity of the militants killed was still being determined but most appeared to be Pakistanis, he said.
A third intelligence official said a third missile was also fired but caused no casualties or damage.
South Waziristan is a known Al-Qaeda and Taliban stronghold.
U.S. forces have carried out nearly 30 air strikes in Pakistan this year, according to a Reuters count, more than half since the beginning of September.
The attacks have killed more than 220 people, including foreign militants, according to a tally of reports from Pakistani intelligence agents, district government officials, and residents.
The United States and Afghanistan have long pressed Pakistan to do more to eliminate the militant sanctuaries in remote ethnic-Pashtun areas no government has ever controlled.
Pakistan, under mounting international pressure to eliminate militants after last month's assault on the Indian city of Mumbai, says the U.S. strikes violate its sovereignty and undermine efforts to fight militancy by inflaming public anger.
India has blamed Lashkar-e-Taiba, a militant group it says was set up by Pakistan to fight Indian rule in the disputed Kashmir region, for the Mumbai attacks.