PESHAWAR, Pakistan (Reuters) - Gunmen stormed a mountaineering base camp in northern Pakistan on Sunday and shot dead nine foreign trekkers and a Pakistani guide as they rested during an arduous climb up one of the world’s tallest peaks, police said.

The night-time raid - which killed five Ukrainians, three Chinese and a Russian - was among the worst attacks on foreigners in Pakistan in a decade and underscored the growing reach of militants in a highland region once considered secure.

One of the victims also held a U.S. passport, a U.S. official said, without giving further details.

Police said a 15-strong gang of attackers wearing uniforms used by a local paramilitary force arrived at about 1 a.m. at a group of tents and ramshackle huts used by hikers scaling the flanks of the snow-covered 8,125-metre Nanga Parbat peak.

The assailants shot dead a Pakistani guard and held other workers at gunpoint, a senior official from the northern Gilgit-Baltistan province said. A Chinese climber managed to escape.

“The gunmen held the staff hostage and then started killing foreign tourists and made their escape,” the official said.

It was the first time foreign tourists had been attacked in the province of Gilgit-Baltistan, where the convergence of the Hindu Kush, Karakoram and Himalayan ranges creates a stunning landscape explored by only a trickle of the most intrepid mountaineers.

Pakistan’s Taliban movement and a smaller militant group both claimed responsibility.

The shootings, which followed several deadly bombings in different parts of Pakistan in the past week, pose a fresh challenge for the new government of Prime Minister Nawaz Sharif, who is battling accusations that his calls for dialogue with insurgents amount to appeasing violent extremists.

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The deaths of the Chinese are a particular blow for Pakistan, which hosted Chinese Premier Li Keqiang last month in a bid to boost trade ties with the Asian giant via their shared border in Gilgit-Baltistan.

China issued a statement condemning the attack and calling for Pakistan to “severely punish” the perpetrators.

Interior Minister Chaudhry Nisar Ali Khan told parliament he had sacked Gilgit-Baltistan’s police chief and another provincial official, an unusual step in Pakistan where senior officials are rarely held accountable for lapses in security.

The move did little to silence critics who asked how gunmen could have slipped past security forces at check points meant to scrutinize visitors to the sensitive mountain region bordering the disputed territory of Kashmir.

CONFLICTING CLAIMS

There were conflicting claims of responsibility for the attack. A Pakistani militant group known as Jundullah, with a track record of attacks in the province, was the first to say it was behind the raid.

“These foreigners are our enemies and we proudly claim responsibility for killing them, and will continue such attacks in the future,” Jundullah spokesman Ahmed Marwat told Reuters by telephone.

The same group has claimed responsibility for a series of attacks in northern Pakistan in recent years, mostly on members of Pakistan’s Shi’ite Muslim minority.

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Pakistan’s Taliban movement, which has its center of gravity closer to the Afghan border, said it had shot the trekkers in retaliation for a U.S. drone strike in May that killed its second in command, Wali-ur-Rehman.

“We wanted to seek revenge for the killing of our leader in the drone attack,” said Taliban spokesman Ehsanullah Ehsan. “Our attacks on foreigners will continue to protest drone strikes.”

It was not immediately possible to reconcile the competing claims. Jundullah and the much larger Pakistani Taliban are among loosely aligned militant groups that frequently share personnel, tactics and agendas. Claims for specific incidents are often hard to verify.

Recent attacks by Pakistani militant groups have tended to focus on security forces and religious minorities, particularly Shi’ites, but foreigners have also been targets in the past.

In 2002, 11 French engineers and technicians working on the construction of submarines for the Pakistan navy were killed along with three Pakistanis in a suicide bombing outside a hotel in the port city of Karachi. In 2009, gunmen attacked the visiting Sri Lankan cricket team in the eastern city of Lahore.

Last weekend, in the southwestern city of Quetta, a suicide bomber attacked a bus carrying women students and then gunmen stormed the hospital treating survivors. More than 20 people were killed.