Pakistani officials say a U.S. drone strike in northwestern Pakistan early Monday has killed 15 people.

Security officials say missiles were fired into a village in North Waziristan, along the Afghan border.

The tribal region has become a hub of al-Qaida and Taliban activity.

Monday's reported drone strike would be the third in three days and the seventh in two weeks in Pakistan, despite Pakistani demands to stop them.

On Sunday, a drone fired four missiles into a compound in the South Waziristan tribal district, killing at least 10 militants.

Intelligence officials said the missiles hit a group of people who had gathered to offer condolences to the brother of another militant killed in a drone strike a day earlier.

The drone strategy has become an increasingly contentious issue between Pakistan and the U.S., following a November strike that mistakenly killed 24 Pakistani soldiers stationed near the Afghan border.

Washington considers drone strikes to be a vital tool in the war against al-Qaida and the Taliban.

Islamabad says the missile attacks are counter-productive, violate the country's sovereignty, kill civilians and fuel anti-U.S. sentiment.

Pakistan's parliament has demanded an apology for the cross-border attack and an end to drone strikes on Pakistani soil, but Washington has refused, prompting Islamabad to block U.S. and NATO supply routes into Afghanistan. Islamabad has not yet reopened the routes, further straining already tense relations between the two sides.