In this May 30, 2012 photo, a Pakistani child is given polio vaccination by a district health team worker outside a children's hospital in Peshawar.

A Taliban ban on polio vaccinations has made thousands of children vulnerable to the crippling disease in Pakistan, one of only three countries in the world where polio is still prevalent.

The ban in north–western tribal areas was announced this week as a protest against U.S. drone attacks on militants in areas near the Afghan border, where the al–Qaeda–linked Taliban have sanctuaries.

"Over 200,000 children have been left without the vaccine, making them vulnerable," said Mazhar Nisar, spokesman for the government’s Polio Monitoring Cell.

The ban was first imposed by Hafiz Gul Bahadur, a North Waziristan–based militant leader who has made a peace deal with the army. He charged that spies disguised as paramedics infiltrate the area to facilitate the drone strikes.

In neighbouring South Waziristan, pro–government militant leader Maulvi Nazeer circulated leaflets in the main town Wana against the vaccination programme.

"In the garb of these vaccination campaigns, the U.S. and its allies are running their spying networks in FATA [the Federally Administered Tribal Areas], which has brought death and destruction in the form of drone strikes," the leaflets said.

The Tirah Valley and Bara area of Khyber district were also pronounced off–limits for polio vaccinators by local militant commander Mangal Bagh, who heads the Lashkar–e–Islam group.

The immunization campaign ran into trouble after the arrest of Dr Shakeel Afridi for allegedly conducting a fake vaccination programme to help U.S. spies locate al–Qaeda leader Osama bin Laden in Pakistan. Bin Laden was killed in a U.S. raid in May 2011.

Afridi was sentenced in May this year to 33 years in jail by a tribal court under treason laws.

The World Health Organization (WHO) on Thursday denied Afridi had carried out any polio campaign, and the Pakistani government has tried to persuade local tribal elders not to link polio vaccinations with the drone attacks, but it has met with no success.

The airstrikes sometimes kill innocent people and lead to resentment that favours the insurgency, but Washington refuses to halt them.

A tribal council of elders convened Wednesday in North Waziristan decided to support the ban on the polio campaign until the attacks are stopped "because innocent people, including children and women, were being killed in such attacks," the Dawn newspaper reported.

The ban is not only a blow to Pakistan’s efforts to distance itself from the two other countries where polio is endemic, Afghanistan and Nigeria, but could also threaten recent gains made against the disease.

Pakistan saw its highest number of polio cases in the past few years, with 198 reported in 2011. So far this year, 23 new cases have been reported, but experts said that decline could be reversed and warned that nearly half of the new cases have been reported in the tribal region.

The WHO and other international aid agencies have been providing medicine and trying to persuade parents to immunize their children but have had little success so far.

"The only way to eradicate polio is to immunize every child, any child that is missed is susceptible to the virus," said Elias Durry, the WHO’s emergency coordinator for polio eradication in Pakistan.

Hurdles to the vaccination campaign have appeared in areas outside the tribal districts because a widespread suspicion exists that the polio vaccine is actually aimed at reducing fertility.

A local volunteer was beaten by an angry father in an Islamabad suburb Tuesday for insisting that children be given the polio drops.

Unknown gunmen attacked a WHO vehicle in the southern port city of Karachi, injuring a doctor and his driver. Both men were supporting the anti–polio campaign.

"Incidents like these highlight the incredible bravery of the more than 200,000 mainly Pakistani volunteers who run every vaccination campaign," the WHO said. "The vaccinators, social mobilisers and frontline staff are the heroes of this campaign." It vowed to remain committed to immunizations in Pakistan despite the problems, and would seek new strategies to improve the country’s vaccination record.

"We will continue to work with the community," Durry said. "We are also implementing a strategy of immunizing people and children at transit points and major highways."