Suspected suicide blast kills at least 14, injures 20 near Pakistan polio centre

At least 12 policemen, one paramilitary officer and one civilian were among the dead, with 20 others injured, officials said, after the explosion ripped through a police van that had just arrived at the centre.

"It was a suicide blast, we have gathered evidence from the scene," Ahsan Mehboob, police chief of Pakistan's province of Balochistan, told Reuters. "The police team had arrived to escort teams for the polio campaign."

Pakistan and neighbouring Afghanistan are the only two countries in the world where polio remains endemic, the World Health Organization says.

Teams in Pakistan working to immunise children against the virus are often targeted by Taliban and other militant groups, who say the campaign is a cover for Western spies, or accuse workers of distributing vaccines designed to sterilise children.

The campaign to eradicate the virus in Pakistan has had some recent success, with new cases down last year, but violence against vaccination workers has slowed the effort.

(Reporting by Syed Raza Hassan; Writing by Tommy Wilkes; Editing by Clarence Fernandez)