More than 57 people were killed and up to 100 injured in two simultaneous explosions in northern Pakistan on Thursday, officials announced.

A spokesman of pro-Taliban militants based in country's tribal areas bordering Afghanistan claimed responsibility for the deadly attacks.

The blasts targeted the civilian workers of a military-run ordnance factory in Wah cantonment area of the garrison town, about 30 kilometres north-west of Pakistan's capital, Islamabad.

"About 57 people have died in the blasts. All of the victims are civilians," the regional police chief Nasir Khan Durrani said, confirming that both were suicide attacks.

One of the explosions took place near a cordon at the main entrance to Pakistan Ordnance Factories (POF) while the second occurred at another gate 500 metres away.

Hundreds of people were leaving the factory on foot, bikes and motorbikes after shift-change when the bombers struck.

Between 40,000 to 45,000 people work at the POF, a sprawling complex of around 20 units manufacturing arms, ammunition and commercial products.

"There were two loud bangs and puffs of smoke. I rushed to the site, it was a horrific scene. The bodies were piled up and the place was littered with limbs and blood," said a factory employee Mohammed Iqbal,

"A Muslim cannot commit such an act," he added.

Maulvi Omar, a spokesman for militant umbrella organization Tehrik-e-Taliban Pakistan (TTP), claimed the responsibility for the suicide attacks, saying these were carried out to avenge the ongoing military operation in Bajaur and Swat districts.

"We have prepared suicide bombers to conduct more such bombings across the country if army actions were not halted," Urdu-language Geo news channel quoted him as saying.

Country's ruling coalition condemned the attack and vowed to continue with the efforts against rising Islamic militancy.

"Such acts of violence will not dampen our resolve to fight extremism," leading Pakistan People's Party's head Asif Ali Zardari, whose wife and ex-premier also died in a suicide-gun-and-bomb attack late last year.

The new civilian government launched peace talks with the militants in March, after coming into power following the February 18 elections.

Although the move helped reduce the suicide bombings that had killed more than 4,000 people in 2007 and early 2008, the violence did completely cease.

The government last month resumed army offensives in troubled Swat valley and the Bajaur tribal district, where hundreds of people, including dozens of troops have died.

The TTP gave a 24-hour ultimatum on Monday to end the security actions. Few hours after the deadline expired, a teenage bomber struck outside the emergency ward of a hospital in Dera Ismail Khan, a town in restive North-West Frontier Province (NWFP), killing 32 people and injuring 20 more.