A suspected U.S. missile strike killed 12 people in northwestern Pakistan on Friday and fighting in another militant stronghold near the Afghan border killed dozens more, officials said.

Two intelligence officials told The Associated Press that missiles struck a home near Miran Shah, the main town in the North Waziristan tribal region, before dawn.

The officials said the death toll climbed from an initial eight to 12 as agents in the area reported more details of the attack. Another 10 people were injured. The identity of the casualties was not immediately clear.

The officials asked for anonymity because they are not authorized to speak on the record to media.

American forces in Afghanistan are stepping up their efforts to hit Taliban and Al Qaeda militants in what they describe as safe havens in Pakistan's wild border regions, despite stiff protests from Islamabad.

With the insurgency in Afghanistan intensifying, U.S. President George W. Bush secretly approved more aggressive cross-border operations in July, current and former American officials have told the AP.

North Waziristan is part of a belt of tribally governed territory where Pakistan's government has little control. The frontier region is considered the most likely hiding place for Osama bin Laden and Al Qaeda No.2 Ayman al-Zawahri.

Since Aug. 20, there have been at least seven reported missile strikes as well as a raid by helicopter-borne U.S. commandos. Pakistani officials insist the latter operation killed 15 people, all of them civilians.

Both the U.S. military and the CIA operate drone aircraft armed with missiles of the type believed to have killed two senior Al Qaeda commanders in Pakistani territory earlier this year.

Pakistani officials warn that the strikes -- especially involving ground troops -- will fan anti-American sentiment in the country and wreck efforts to win over moderate tribal leaders and bring economic development to the impoverished border region.

Authorities negotiated a peace deal with tribes in North Waziristan earlier this year. Similar efforts have failed or broken down on other parts of the northwest.

On Friday, army spokesman Maj. Murad Khan said 32 militants and 2 soldiers had died in the previous 24 hours in the Bajur region. Iqbal Khattak, a local government official, put the total for the 24-hour period higher, saying about 60 militants have died.

Officials say hundreds of militants have died there in a weeks-long offensive into Bajur. An estimated 500,000 people have fled their homes. Officials acknowledge that civilian have been killed and villages badly damaged in the fighting.