At least 12 soldiers have been killed and around a dozen people wounded after three roadside bombs targeting a polio vaccination team exploded.
The bombs went off as the team passed through the country’s northwest tribal region.
Gunmen frequently attack polio vaccination workers in Pakistan. Militants accuse them of being Western spies or part of a plot to sterilise Muslims.
One militant leader said he would only allow vaccinations in his area if US drone strikes stopped.
The World Health Organisation (WHO) said Pakistan is the only polio-endemic country in the world where polio cases rose from 2012 to 2013.
There were 91 cases in 2013 but only 58 the year before. WHO has warned that Peshawar is the largest reservoir of endemic polio viruses in the world.
Pakistan is one of three countries in the world, along with Afghanistan and Nigeria, where polio still exists.
Meanwhile, the Pakistani Taliban has announced a one-month ceasefire aimed at reviving peace talks after receiving what it said were government assurances it would not be attacked.
The senior leadership of the Taliban advises all subgroups to respect the Taliban's call for a ceasefire and abide by it and completely refrain from all jihadi activities in this time period.
Peace talks failed after the Taliban bombed a bus of policemen and a faction of the Taliban claimed to have executed 23 kidnapped men from a government-run paramilitary force.
Their bodies were never found.
The Pakistani military responded by bombing areas they identified as militant hideouts. A military spokesman said the attacks destroyed key hideouts and killed dozens of militants.