DERA ISMAIL KHAN, Pakistan—Two suspected U.S. missile strikes Friday on villages close to the border with Afghanistan killed at least 12 people, most of them militants, Pakistani intelligence officials said.

American forces recently ramped up cross-border operations against Taliban and al-Qaida militants in Pakistan’s border zone with Afghanistan—a region considered a likely hiding place for Osama bin Laden.

Two missiles believed to have been fired from U.S. unmanned drones launched from neighboring Afghanistan hit the villages in North Waziristan just before dusk, according to the officials who spoke on condition of anonymity because they were not authorized to speak to the media.

A missile strike in one village killed at least 12 people, while there were no reported casualties in the other, they said. The officials did not identify the victims.

Chief Pakistani army spokesman Maj. Gen. Athar Abbas said officers were investigating the reported strikes, but could not confirm them. U.S. officials in Afghanistan or Washington rarely acknowledge the attacks.

Earlier this week, officials said that a suspected U.S. missile strike on a Taliban commander’s home in Pakistan killed six people late Tuesday.

Pakistan says the attacks often result in civilian casualties and serve to fan extremism. American officials complain that Pakistan was unwilling or unable to act against the militants, straining ties between the two anti-terror allies.

Militants in the border region are blamed for rising attacks on U.S. troops in Afghanistan and attacks within Pakistan, including the Sept. 20 truck bombing of the Marriott Hotel in Islamabad that killed more than 50 people.

On Friday, Pakistan’s Interior Minister chief Rehman Malik said the country’s war against Islamic extremists will go on until it is “terrorism-free.”

Previous Pakistani military campaigns against Islamic militants in the wild tribal belt along the Afghan frontier were halted too soon, he said—an apparent reference to the policies of former President Pervez Musharraf.

Malik said the current government, which came to power after February elections and forced Musharraf to resign in July, will fight until militants are either killed or forced to flee Pakistan.

“There is no other option,” Malik told Express News television. “We will not stop any operation unless we reach its logical conclusion. That means that this war will continue until we make Pakistan terrorism-free.”

Pakistan’s army is battling militants in at least three areas of the northwest. The most intense fighting has been in the Bajur tribal region, where the military claims to have killed 1,000 rebels for the loss of about 60 troops.

The country’s faltering efforts so far have been met with a blur of suicide bombings that have killed nearly 1,200 people since July 2007, according to army statistics released this week.

The U.N. reacted to the hotel blast on Thursday by ordering the children of its international staff out of the city—putting it on a par with trouble spots such as Kabul, Afghanistan and Mogadishu, Somalia.

It insisted the move was temporary and would not affect its operations.

Britain announced Wednesday it was repatriating its diplomats’ children and other countries may follow suit. Pakistan has long been a non-family posting for U.S. diplomatic staff.