The Pakistani government's anti-polio campaign began nationwide on Monday but it was not able to kick off in the restive northwestern region of Waziristan.
Islamabad said the three-day polio eradication campaign would target 34 million children countrywide under the age of five.
Pakistani health officials said last week that at least 160,000 children in North Waziristan and 80,000 in South Waziristan would be affected if polio drops were not given to them.
Vaccination problems have led to a rise in polio cases in Pakistan. Last year, Pakistan recorded 198 cases of the disease - the highest number in a decade. Polio is also endemic in neighboring Afghanistan.
The Taliban threat
The authorities said they were postponing the campaign in Waziristan after the Taliban leader Hafiz Gul Bahadur banned inoculations, claiming the drive was similar to a hepatitis vaccination program run by the imprisoned Pakistani doctor Shakeel Afridi, which allegedly helped the CIA find al Qaeda's former chief Osama bin Laden.
Bin Laden was eventually killed by the US Special Forces in his Abbottabad hideout last year in May.
Earlier this year, a Pakistani court sentenced Dr Afridi to 33 years in prison after charging him with treason.
Pakistani officials said on Monday that the fighting between the Taliban warlord Mangal Bagh and government troops also made it difficult to run the campaign in the Khyber district of the north-western Khyber Pakhtunkhwa (KP) province.
"The campaign has been postponed in North and South Waziristan, and the Bara (district) of Khyber," said Mazhar Nisar, the head of the polio monitoring cell at the prime minister's secretariat.
Shahnaz Wazir Ali, an adviser to Pakistani Prime Minister Raja Pervez Ashraf, told DW that the Dr Afridi episode had made it difficult for the authorities to conduct this campaign.
"People think that agents like Dr. Shakeel Afridi work in polio immunization teams, and that might put their lives at risk," he said, adding that the anti-polio campaigns did not involve blood and DNA tests.
Ali told DW that the anti-polio campaign was not anti-Islam, as propagated by some groups, and was merely the need of the hour.
Karachi-based journalist Nusrat Amin told DW that anti-progressive forces in countries such as Pakistan had often opposed campaigns that were aimed at improving people's lives.
"Successive governments have always succumbed to tribal pressures, so it doesn't surprise me if the government chose to postpone the drive," said Amin.
For his part, Wajahat Malik, an Islamabad-based social activist and filmmaker, told DW that "the polio eradication campaign has lost its credibility in Pakistan which is rife with conspiracy theories," since the Dr Afridi affair.
Malik also said that the Pakistani state not only had no writ in North Waziristan, but its presence in the whole of the tribal belt was nearly non-existent.
"The Taliban rule most of the tribal areas of Pakistan. Even in the 'tribal agencies' that have supposedly been cleared of militants, there is no government to be seen on the ground."
Author: Shamil Shams
Editor: Anne Thomas