The early Wednesday attack was the biggest such attack this year and the second since Prime Minister Nawaz Sharif took office.

Two missiles hit a house near the main market in Miranshah, the provincial capital of the tribal region of North Waziristan in the attack.

Many were wounded in the attack, local tribesman Kaleemullah Dawar said, but rescuers delayed for fear of falling victim to a second attack, a common tactic with drone strikes.

"It was not possible for the people to start rescue work for some time, as the drones were still flying over the area," Dawar said.

Sharif, who won elections in May, has called for an immediate end to US drone strikes on the grounds that they are a breach of Pakistan's sovereignty.

The US claims it is attacking militants in the remote areas, but Pakistanis says most of the victims are civilians.