Six people died Monday in the bombing of a clinic where health care teams were giving polio vaccinations in the northern city of Peshawar, Pakistani authorities told Efe.

Among the dead are four police officers who were guarding the clinic and two civilians, one of then a volunteer with the vaccination campaign, according to a police officer in Peshawar, capital of Khyber-Pakhtunkhwa province.

The attack occurred about 8:30 a.m. at a medical center in the Suleiman Khel zone, where several vaccination teams were setting up for the workday.

The bomb also wounded about 10 people, two of whom are in critical condition, the head of Peshawar's hospital, Arshad Javed, told the media.

Since last December, attacks on polio vaccination have killed some 30 people in different parts of Pakistan, especially in Khyber-Pakhtunkhwa and the neighboring Tribal Agencies, on the border with Afghanistan.

The most recent incident occurred a week ago when a civilian died and a member of the security forces was wounded when a bomb exploded as a vaccination team was passing by in Bajaur, north of Peshawar.

Although the Taliban do not usually stage actions of this type against the immunization campaign, other Islamists have made threats against the teams.

Some fundamentalists say the anti-polio campaign is part of a Western plot to sterilize Muslims.

Suspicions about vaccination efforts increased after it emerged that the CIA organized a fake vaccination campaign against hepatitis B in order to find Osama bin Laden, who was killed by U.S. special forces on May 2, 2011, during a raid on the al-Qaeda leader's home in the Pakistani city of Abbottabad.

Pakistan is one of only three countries - Afghanistan and Nigeria are the others - where polio is still endemic. EFE