Pakistani politician Imran Khan has been threatened for describing polio vaccination workers as "soldiers of Islam".

A senior member of Tehreek-i-Insaaf (PTI), Shireen Mazari, told the news agency AFP that Khan had received the threat from the armed group Ansarul Mujahideen after making positive comments about health workers and condemning those who undermined them.

Those attacking polio workers and policemen deputed to protect them, are not doing any justice to humanity, Islam and people of Khyber Pakhtunkhwa and Pakistan. Imran Khan

The country is one of only three in the world where the disease is endemic, but attempts to contain it have suffered because of intimidation and violence.

Since July 2012, 31 people have been killed in Taliban-led attacks on anti-polio campaigners.

Most recently, two policemen providing security to polio vaccinators in Swabi were killed when gunmen on a motorbike attacked them.

In a separate incident, unidentified gunmen opened fire on polio workers in Peshawar, killing one.

The former cricket star made the remarks on Wednesday at a hospital in the northern province of Khyber Pakhtunkhwa, where his party leads the government.

Pakistan has reported 75 cases of polio this year, many of them from this area.

"Those attacking polio workers and policemen deputed to protect them, are not doing any justice to humanity, Islam and people of Khyber Pakhtunkhwa and Pakistan," Khan said.

"Polio workers are mujahid (soldiers of Islam) and we stand by them."

He promised to lead a new anti-polio campaign, even administering the medicine to children himself.

Several groups oppose polio vaccination campaigns, claiming they are either a front for espionage or an attempt to sterilise Muslims.

Last year the Pakistani Taliban banned polio vaccinations in Waziristan.

With security concerns high, polio vaccination teams lack access to the North and South Waziristan regons, meaning that about to 290,000 children have been prevented from receiving vaccinations.

Nationally, 90 percent of polio cases occur among ethnic Pashto families, many of whom live in the northwest of Pakistan.