Pakistan 'policeman killed' guarding anti-polio worker
A policeman giving protection to an anti-polio programme in Pakistan has been shot dead, police say.
He was shot while guarding the main gate of a house in Khao Killay village in Mardan district as a worker administered the vaccine inside.
The killing is the latest in a spate of deadly attacks against vaccination workers in the country.
In December at least eight people engaged in polio vaccinations were shot dead in Karachi and the north-west.
Along with Afghanistan and Nigeria, Pakistan is one of only three countries where polio is still endemic.
No group has said it carried out Tuesday's attack, but the Taliban have threatened anti-polio efforts.
The militants have accused health workers of working as US spies and say the vaccine makes children sterile.
In January, a policeman was killed in a similar attack in the town of Swabi.
Two days after that attack, two polio vaccination workers were killed in a landmine blast in the Kurram tribal region of the country. Correspondents say the mine was probably planted to target the area's Shia Muslims, rather than vaccination workers.
On 1 January seven charity workers, six of them women, were shot dead in the Swabi area.
Correspondents say it is not clear if they were targeted because their charity offered vaccinations or education for girls.