ISLAMABAD (AFP) - A militant accused over one of Pakistan's most notorious recent terror attacks, the massacre of 10 foreign climbers in the country's far north in 2013, escaped from jail on Friday, officials said.

Gunmen stormed a base camp at Nanga Parbat, Pakistan's second-highest mountain, in June 2013 and shot dead the mountaineers along with their Pakistani guide in an attack that shocked the world and badly damaged Pakistan's climbing tourism industry.

One of the key suspects, Habib-ur-Rehman, managed to escape from prison in Gilgit in northern Pakistan in the early hours of Friday morning, along with another inmate held over a different attack on security forces. Two other prisoners tried to escape with them, but one was recaptured and the other, also accused over the Nanga Parbat massacre, was killed.

"Four militants jailed in the district prison of Gilgit attempted to escape. They were countered by forces but two of them succeeded in their attempt," Mr Liaquat Ali, a senior administration official in Gilgit, told AFP by telephone. The escaped militants were awaiting trial over the attacks.

"Among them, one was Habib-ur-Rehman, accused of killing foreign mountaineers on Nanga Parbat in 2013 and the other inmate Liaquat was involved in an attack on security forces in Chilas region."

Mr Ali said they broke out at around 2.45am local time and security forces have cordoned off the area as the search for the escapees.

Another senior official in the district, Mr Muhammad Ajmal Bhatti, confirmed the incident and said the authorities had "locked down the city to comb for the escaped militants".

Northern Pakistan is home to some of the world's tallest mountains, including K2, the world's second-highest peak.

Mountaineers have long been drawn to the area by the challenging climbs, but tourism was badly hit by the Nanga Parbat killings.

On Monday, the police announced the creation of a new 50-strong specialist high-altitude unit in a bid to protect climbers and trekkers in the northern Gilgit-Baltistan region.

Militant groups have organised several mass jailbreaks in Pakistan in recent years, including one in the northwestern town of Bannu in 2012 that sprung 400 prisoners.