A suspected U.S. missile strike hit a village well inside Pakistani territory Wednesday, killing at least six alleged militants in an attack that could raise tensions between the anti-terror allies, officials said.

The missile struck a house in Bannu district, which is a part of northwest Pakistan where Al Qaeda and Taliban have found refuge, but does not directly border Afghanistan.

Two Pakistani intelligence officials said their agents reported foreigners from Central Asia were among the dead. The intelligence officials spoke on condition of anonymity because they were not authorized to speak to media.

The U.S. has made nearly 20 missile strikes in northwest Pakistan since mid-August against Al Qaeda and Taliban militants blamed for rising attacks against foreign forces in Afghanistan.

The missiles are believed fired from unmanned planes launched in Afghanistan, where some 32,000 U.S. troops are fighting the Taliban and other militants.

Pakistan has loudly protested the strikes as violations of its sovereignty, but the attacks have not stopped, leading to speculation by some analysts the two nations have a secret deal on the attacks.

All the attacks since August have been in villages in north and South Waziristan, two semiautonomous tribal regions where the government has a very limited presence.

Bannu is considered a "settled area", which means it falls under the control of the regional government, and as such Monday's attack could provoke more anger among by Pakistan's leaders. It begins roughly 18 mile from the frontier.

Pakistan has insisted it does not get advance warning of such attacks, and has demanded the U.S. share intelligence and let Pakistan go after targets on its own.

The United States rarely confirms or denies the strikes, which are believed to be carried out by CIA.

Even as the strikes have picked up, U.S officers in Afghanistan have stressed improved day-to-day Pakistani cooperation in squeezing militants nested along both sides of the lengthy, porous border.

U.S. military officials said troops in Afghanistan coordinated with Pakistan on Sunday in shelling insurgents inside Pakistan who were launching rockets at the foreign troops. Pakistan's official statement on the matter referred only to militant activity in Afghanistan.

In the past month, NATO and Pakistan also have cooperated in so-called Operation Lion Heart — a series of complementary operations that involve Pakistani army and paramilitary troops, and NATO on the Afghan side, said Col. John Spiszer, U.S. commander in northeast Afghanistan.

"What we have done is worked very hard to refocus our ... intelligence, surveillance, reconnaissance assets to do everything we can to identify transiting across the border," he told a Pentagon news conference in Washington on Tuesday.

Commanders hope pressure on both sides of the border will eventually mean militants will be "running out of options on places to go," Spiszer said.

U.S. officials also have praised Pakistani military offensives against militants in its border region, including an operation in the Bajur tribal area that the army says has killed more than 1,600 alleged insurgents.

Besides questions of sovereignty, Pakistani officials say the U.S. missile strikes are counterproductive because they often kill civilians and deepen anti-American and anti-government sentiment along the border.

But U.S. Gen. David Petraeus has defended them, saying at least three top extremist leaders, whom he did not identify, have been killed in recent months in the attacks.