The Pakistan government has suspended the anti-polio drive and post-campaign evaluation following the increasing number of attacks on polio workers in different parts of the country.
The countrywide campaign to administer anti-polio drops to 39 million children under five years of age was launched on Monday and Friday was the last day following which the evaluation of the drive was to take place.
However, the campaign, involving 260,000 polio workers, ran into trouble after reports that several children were taken to hospital as they fell sick after being administered the anti-polio vaccine in some areas of Peshawar.
Following the reports, unidentified gunmen shot dead security personnel escorting a team of polio workers in different incidents in northwest Pakistan.
In another incident, a female polio worker was killed and another injured in Chaman area in Balochistan.
The National Emergency Operation Centre (EOC) for polio issued a letter asking all the provinces to stop the campaign and prevent further damage.
The uncertain and threatening situation for the front line polio workers has emerged and we need to save the programme from a further major damage, said the letter issued by the EOC.
Pakistan is one of the three countries where polio is still endemic. The campaign aimed to provide anti-polio medicine to children in all four provinces as well as Pakistan occupied Kashmir and Gilgit-Baltistan.