Pakistan on Monday postponed a polio immunisation campaign in parts of its tribal belt, jeopardising the health of more than 350,000 children after the Taliban banned inoculations.
Local Taliban and Pakistani warlord Hafiz Gul Bahadur, whose followers are fighting Western troops in Afghanistan, banned the vaccinations in the northwestern region of Waziristan to protest against US drone attacks.
They have condemned the immunisation campaign, which began nationwide on Monday, as a cover for espionage.
Pakistani doctor Shakeel Afridi was jailed for 33 years in May after helping the CIA find Osama bin Laden using a hepatitis vaccination programme as cover.
Fighting between government troops and local warlord Mangal Bagh also made it difficult to innoculate all children in Khyber district, officials said.
"The campaign has been postponed in North and South Waziristan and Bara (district) of Khyber," Mazhar Nisar, in charge of the polio monitoring cell at the prime minister's secretariat, told AFP.
Officials in Miranshah, the main town of North Waziristan, said a meeting of tribal elders to discuss immunisation had been postponed due to a military curfew.
In Khyber, administration official Irfanullah Wazir told AFP that the target was to vaccinate 200,163 children, but conceded the campaign would be affected in parts of Bara and the Tirah valley, where 111,556 children need the drops.
"We will make every effort to reach the maximum children in those areas, with the help of security forces and lashkars (pro-government tribal militias)," Wazir said.
Fawad Khan, director of health services in the tribal belt, told AFP last week that at least 160,000 children in North Waziristan and 80,000 in South Waziristan would be affected if polio drops are not administered.
Pakistan says 34 million children under five will be targeted in the three-day polio immunisation campaign from Monday to Wednesday.
The prime minister's office said 22 vaccination points had been established on the Afghan-Pakistani border, but expected that a "substantial proportion" of children in Bara, South and North Waziristan would not be accessed.
The Lancet medical journal has said vaccination problems led last year to Pakistan's highest number of polio cases in a decade, 198, compared to 144 in 2010.
Polio remains endemic only in Afghanistan, Pakistan and Nigeria.
The highly infectious disease affects mainly the under-fives and can cause paralysis in a matter of hours. Some cases can be fatal.