An explosion possibly caused by a missile strike killed five suspected foreign militants near the Afghan border on Friday, Pakistani officials said.
The blast occurred in a village in the North Waziristan region, part of Pakistan's wild tribal belt that serves as a base for Taliban militants and fugitive al-Qaida leaders.
U.S. commanders who blame those sanctuaries for rising violence in neighboring Afghanistan appear to be stepping up their efforts to hit militants inside Pakistan.
Two intelligence officials, citing local informers, told The Associated Press that drone aircraft were seen above the village of Gurwak before Friday's blast and that they believed the aircraft had fired missiles.
The officials, who asked for anonymity because they are not authorized to speak publicly, told The Associated Press that five suspected foreign militants were killed and several other people were injured. They provided no other details of the victims' identity.
Army spokesman Maj. Gen. Athar Abbas confirmed the explosion and said the military had sent a team to investigate what had happened.
String of previous U.S. missile strikes
The U.S. military and the CIA operate drone aircraft believed to have carried out a string of missile strikes that killed at least two senior al-Qaida commanders earlier this year.
Foreign forces in Afghanistan are also authorized to pursue militants a short distance over the poorly demarcated and oft-disputed Pakistani frontier and to return fire over the border. They also can take action to avert an "imminent threat."
On Wednesday, U.S. troops ferried by helicopter to a village in Pakistan's South Waziristan region carried out a highly unusual ground attack on a militant target.
Pakistani officials claim that 15 people, including civilians, were killed during the pre-dawn operation, though the target and results of the raid in an area inaccessible to reporters remain unclear.