PESHAWAR, Pakistan (Reuters) - A pilotless U.S. drone aircraft fired a missile in northwest Pakistan on Saturday, killing 13 people including some foreign militants, security officials and residents said.

Hours later, Pakistani Taliban militant leader Baitullah Mehsud claimed responsibility for a shooting at a U.S. immigration center in New York in which a gunman killed 13 people, saying it was revenge for U.S. drone attacks in Pakistan.

U.S. officials were not immediately available for comment about Mehsud’s claim, but Pakistani security analysts dismissed it as a publicity stunt.

The New York Times quoted representative Maurice Hinchey, whose district includes the town of Binghamton in New York state where the shooting took place, as saying indications were the gunman was an immigrant from Vietnam.

With the Afghan insurgency intensifying, the United States began launching more drone strikes against al Qaeda and Taliban militants on the Pakistani side of the border last year.

Since then, about 35 U.S. strikes have killed about 350 people, including mid-level al Qaeda members, according to reports from Pakistani officials, residents and militants.

The attack Saturday was in the North Waziristan region, a stronghold of al Qaeda and Taliban militants on the Afghan border, about 35 km (20 miles) west of the region’s main town of Miranshah at about 3 a.m. (5 p.m. EST on Friday).

“The missile hit a house where some guests were staying,” one intelligence agency official said, referring to foreign militants. “We have information that 13 people were killed including some guests.”

Later, a suicide bomber was killed as he approached a military convoy. His explosives went off, killing three passersby, witnesses and a hospital official said.

Many al Qaeda and Taliban militants fled to northwestern Pakistani border regions such as North Waziristan after U.S.-led forces ousted the Taliban in Afghanistan in late 2001.

From the remote ethnic Pashtun tribal lands that have never been governed by any Pakistani government, the militants have orchestrated the Afghan war and plotted violence beyond.

“MY MEN”

Nuclear-armed, U.S. ally Pakistan objects to the missile strikes, saying they are a violation of its sovereignty and are counter-productive.

Officials say about one in six of the strikes over the past year caused civilian deaths without killing any militants, and that fuels anti-U.S. sentiment, complicating the military’s struggle to subdue violence.

The concentration of strikes in Waziristan was also pushing some militants eastwards, deeper into Pakistan, they say.

Taliban leader Mehsud said Tuesday his group had carried out an assault on a police training center in the Pakistani city of Lahore in retaliation for U.S. drone attacks. He vowed more attacks in Pakistan, Afghanistan and the United States.

Security analysts say Mehsud does not have the capacity to conduct attacks in the United Sates by himself but he is part of an al Qaeda-led network that does have global reach.

Mehsud told Reuters by telephone that two men, one a Pakistani and the other a “foreigner,” had carried out the shooting in the United States Friday.

“I accept responsibility. They were my men. I gave them orders in reaction to U.S. drone attacks,” he said, adding one of the attackers had escaped and telephoned him.

Pakistani analysts were skeptical.

“It seems it’s a move to boost his image. To me, it’s just bluster and bluff,” said Talat Masood, a retired general turned analyst. “It shows he’s under tremendous pressure.”

Competition has intensified between Taliban factions in the northwest and the drone strikes are taking a toll, analysts say.

Last month, the United States announced a $5 million reward for information leaded to Mehsud’s location or arrest.

“He doesn’t have the capacity (to attack in the United States),” said defense analyst Hasan Askari Rizvi.