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Pakistan's army on Friday disputed reports that its security forces had tipped off insurgents at bomb-making factories after getting intelligence about the sites from the United States.

The Foreign Ministry also lodged a protest with the American embassy over a purported attack on a Pakistani military post — the latest signs of strained relations since the U.S. killed Osama bin Laden last month without notifying officials here ahead of time.

The army called the assertions of collusion with militants "totally false and malicious."

American officials told The Associated Press in early June that they'd shared satellite information with Pakistan about two militant bomb-making factories. Within 24 hours, they said they watched the militants clear out the sites, raising suspicions that the Pakistanis had shared the information.

In a carefully worded, two-paragraph statement Friday, the army never says the U.S. shared intelligence on the sites in question. But it said its attempts to destroy four militant bomb-making factories only partly succeeded because intelligence on two of the sites was wrong.

It also was unclear about the sites' exact location and does not say when the raids occurred. But it's likely to further add to tensions between the U.S. and Pakistan, which have been unusually high since the U.S. raid that killed bin Laden.

Various media accounts said the factories were in the Waziristan stretch of Pakistan's tribal belt, where al-Qaida and Taliban fighters have long proliferated. The intelligence sharing was part of a U.S. attempt to improve the relationship with Pakistan.

Bin Laden's presence there has only added to U.S. suspicions that elements within Pakistan's powerful security establishment were playing a "double game" by colluding with some militants while going after others.

Pakistani leaders have denied knowing that bin Laden was in Abbottabad — and U.S. officials have said there's no evidence yet that the upper ranks of the Pakistani military or civilian leadership helped hide him. But Pakistanis are furious that the U.S. staged the raid without any warning or Islamabad's consent.

They also are angry over a series of recent media reports that seem to cast more doubt on their activities, including the one about the factories.

Also Friday in Pakistan's northwest, security forces backed by artillery killed 12 Islamist militants in a tribal region where insurgents have been mounting cross-border attacks from Afghanistan, a government administrator said.

The attacks have upset Pakistan, which says they are happening because U.S. and NATO forces are not doing enough to protect the territory on the Afghan side. Western forces have had the same complaints about Pakistan's activities on its side of the boundary.

The search operation Friday took place in the Mamund area of the Bajur tribal region. It came a day after more than 200 militants launched a cross-border attack on the same area, killing five people.

Government official Tariq Khan said Friday's search came after fresh intelligence reports on militants coming from Afghanistan to the area to target tribal militiamen and troops stationed there.

"We are deploying additional security forces in our villages and towns located near the Afghan border to protect our areas," he said, adding that tribal elders were asked to remain vigilant and alert authorities of any militant movement.

The information could not be verified independently because access to the area is restricted.

The Pakistani Foreign Ministry said Friday it had lodged protests with the U.S. and Afghanistan over incursions across the border.

In a statement, it said it had told the U.S. Embassy in Islamabad of its "serious concern" about an alleged air incursion by NATO aircraft 1.5 miles (2.5 kilometers) inside the Mohmand tribal area, in which a Pakistani military post was "attacked."

Ministry spokeswoman Tehmina Janjua told The Associated Press the incident occurred around 9 a.m. Friday, but that no casualties were apparently involved. The ministry has requested a joint probe into the alleged incursion.

The ministry said it also summoned a top Afghan embassy official to lodge a protest about the insurgent incursions into Bajur.

U.S. officials said they were looking into the allegations. Afghan officials could not immediately be reached for comment.

Pakistan's military has launched offensives aimed at clearing Bajur of al-Qaida and Taliban fighters, but the militants there still retain the ability to strike. The U.S. has supported Pakistan's efforts to clear Bajur, but it has also pushed it to go after militants in North Waziristan. Many of the militant groups in that region are focused on attacking Western forces in Afghanistan.

However, Pakistan has resisted the appeals to go into North Waziristan. It says it is too stretched fighting militant groups that have staged attacks on its soil to open up a new front. Some critics believe Pakistan wants to remain on good or at least neutral terms with the North Waziristan militants so that it has allies in Afghanistan once the U.S. withdraws from the region.

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Associated Press writers Matiullah Achakzai in Chaman and Anwarullah Khan in Khar contributed to this report.