One villager said nine bodies had been recovered from the rubble and that people are searching for more casualties.

No confirmation

Admiral Mike Mullen, the United States' most senior military officer, on Sunday declined to confirm or deny the suspected attacks.

"I'm not going to talk a lot about our operations specifically," Mullen said in an interview on the US channel, Fox News.

"There is a continuing concern with the existence of the safe haven in Pakistan, and that has to be addressed, has been addressed and needs to continue to be addressed," he said.

Suspected US drone attacks began increasing in frequency last year.

Pakistan believes the civilian casualties caused by US drone raids have fuelled support for opposition fighters.

But US officials believe the attacks have killed a number of high-ranking al-Qaeda and Taliban members.

Shah Mehmood Qureshi, Pakistan's foreign minister, who was in Washington to take part in the Obama administration's review of policy on Afghanistan and Pakistan, said last week that he had asked US officials to transfer the drone technology to Pakistan.

No public response was given by the US.