KARACHI, Pakistan — Gunmen shot and killed five women working on UN-backed polio vaccination efforts in two Pakistani cities on Tuesday, officials said, a major setback for a campaign that international health officials consider vital to containing the crippling disease but which Taliban insurgents say is a cover for espionage.
Pakistan is one of three countries where polio is endemic. Militants, however, accuse health workers of acting as spies for the United States and say the vaccine makes children sterile.
Taliban commanders in the troubled northwest tribal region have also said vaccinations cannot go forward until the United States stops drone strikes in the country.
Insurgent opposition to the campaign grew last year after it was revealed that a Pakistani doctor ran a fake vaccination program to help the CIA track down Al Qaeda chief Osama bin Laden, who was hiding in the town of Abbottabad in the northwest.
The Taliban have targeted previous antipolio campaigns, but this has been a particularly deadly week.
The government is in the middle of a three-day vaccination drive targeting high risk areas of the country as part of an effort to immunize millions of children under the age of five.
‘‘Such attacks deprive Pakistan’s most vulnerable populations — especially children — of basic life-saving health interventions,’’ said a statement jointly released by the government and the UN. ‘‘We call on the leaders of the affected communities and everyone concerned to do their utmost to protect health workers and create a secure environment so that we can meet the health needs of the children of Pakistan.’’
The women who were killed Tuesday — three of whom were teenagers — were all shot in the head at close range.
Four of them were gunned down in the southern port city of Karachi, and the fifth in a village outside the northwest city of Peshawar. Two men who were working alongside the women were critically wounded in Karachi.
The attacks in Karachi were well-coordinated and occurred within 15 minutes in three areas of the city that are far apart, said police spokesman Imran Shoukat.
In each case, the gunmen used 9-millimeter pistols.
Two of the women were killed while they were in a house giving children polio drops, said Shoukat. The other two were traveling between houses when they were attacked, he said.
On Monday another person working on the antipolio campaign, a male volunteer, was gunned down in Karachi.
Taliban militants also killed three soldiers in an ambush of an army convoy escorting a vaccination team in the northwest.
Officials in Karachi responded to the attacks by suspending the vaccination campaign in the city, said Sagheer Ahmed, the health minister for surrounding Sindh Province. The campaign started on Monday and was supposed to run through Wednesday, he said.
Immunization was suspended in Karachi in July as well after a local volunteer was shot to death and two UN staff were wounded.
There were conflicting reports about whether the campaign was temporarily suspended in Khyber Pakhtunkhwa Province, where the fifth woman was killed Tuesday.
The statement released by the government and the UN said the drive was halted in Sindh and Khyber Pakhtunkhwa.
But Janbaz Afridi, a senior health official in Khyber Pakhtunkhwa, said he had not received any suspension orders and planned to continue the campaign on Wednesday.