Islamabad, March 11 (IANS): In continuing attacks on officials administering anti-polio drops in Pakistan, two police officials assigned to a polio vaccination team were gunned down Tuesday in Khyber Pakhtunkhwa province, media reported.

The two policemen were reportedly returning to their respective homes after performing their duties when they were targeted by unidentified gunmen in Garo Ahmed area of Dera Ismail Khan, Dawn online reported

Both died on the spot.

Pakistan is one of the few remaining countries where polio persists. In most cases, the disease is found in the northwest, where militants hinder efforts by polio vaccination teams to reach children.

The World Health Organisation (WHO) had Jan 17 declared Pakistan's troubled north-western city of Peshawar as the world’s “largest reservoir” of endemic polio and called for urgent action to boost vaccination.

Meanwhile, Prime Minister Nawaz Sharif expressed concern over preventing the polio immunisation campaign through force. He also said that no compromise would be made on the National Emergency Action Plan for polio eradication.

"A health emergency had been imposed in the country to eradicate polio. Polio vaccine should be available to every child in the country," he said while chairing a meeting of the Polio Task Force at the PM Secretariat in Islamabad.

Militant groups see vaccination campaigns as a cover for espionage, and there are also long running rumours about polio drops causing infertility.

An increasing number of polio cases have given rise to fears that Pakistanis could face travel restrictions over the growing number of polio cases in the country.