Peshawar, Pakistan (CNN) -- Seven teachers were kidnapped Thursday from Pakistan's volatile tribal Khyber Agency for having supported a polio vaccination campaign, an official told CNN Saturday.
"They were not the polio workers, but they had been picked up by the unknown kidnappers for allowing polio vaccination in their school, Hira Public School," said Nasir Khan, the assistant political agent of Bara Teshil of Khyber Agency.
"They were not directly related to polio vaccination, but had supported the workers as volunteers during the recent vaccination drive, and that's why they had been kidnapped," he added.
Khidmat Kalaq Foundation, a local charity that runs the school, and a jirga led by a tribal elder were in talks to resolve the issue, he said.
The school is in the Sipah area of Bara District in the Federally Administered Tribal Area.
According to an official who was not authorized to speak to the media and asked not to be identified, a three-day anti-polio campaign had ended Friday.
The World Health Organization's assistant director-general for polio, emergencies and country collaboration said Saturday that the kidnapped teachers did not appear to have been involved in a polio vaccination campaign, as original reports suggested.
"We don't have anything to corroborate that whatsoever," Dr. Bruce Aylward told CNN in a telephone interview from Geneva, citing his contacts in the country who have spoken with people in the area where the abductions occurred. "What we have heard is that that's not the case."
At least 16 cases of polio have been reported this year in Khyber Agency; law and order problems in Bara have left it particularly vulnerable to the disease, which has been declared eradicated from adjacent India.
Anti-polio campaigns have been targeted by militants here since U.S. intelligence used a fake vaccination program to help in its hunt for Osama bin Laden in 2011. Under cover of the program, the CIA sought to collect DNA samples from relatives of the al Qaeda leader to verify his presence in a compound in Abbottabad.
Since July 2012, at least 22 polio workers have been killed.
The polio campaign has a history of controversy in Pakistan. Some mullahs have preached against it, claiming falsely that the oral vaccine leaves Pakistani children sterile.
Last year, a Taliban commander in northwest Pakistan announced a ban on polio vaccines for children in the region as long as the United States continues its campaign of drone strikes.
Polio, which can cause permanent paralysis in hours, remains endemic only in Pakistan, Nigeria and Afghanistan.
After its case count spiked sharply last year, Pakistan stepped up eradication efforts. The numbers fell from 198 in 2011 to 58 in 2012 but that progress has stopped: Pakistan is the only one of the three countries where polio is endemic to see its numbers go up this year, WHO's Aylward said.
As of November 19, it has seen 63 cases this year versus 54 cases as of that date last year, he said.
A second concern is spread of the infectious viral disease from Pakistan to other parts of the world -- cases diagnosed this year in Afghanistan have been linked directly to virus from Pakistan, he said.
CNN's Tom Watkins contributed to this report