Seven policemen have died after unidentified gunmen attacked them while they were guarding medical workers administering polio vaccinations in Pakistan, in the latest violence against efforts to eradicate the crippling childhood disease.
The policemen were killed in two attacks in the city of Karachi, a sprawling port metropolis of more than 20 million people that has been plagued by ethnic, sectarian and political violence for years.
"One took place at the three policemen who were escorting a polio team, the policemen were on foot when they were attacked," said an official, Ali Asif.
"In the second incident, four policemen in a police van were targeted," he said.
Polio, which can cause lifelong paralysis, is now endemic in only two countries, Pakistan and Afghanistan.
Provincial Home Minister Sohail Anwar Siyal, told the private Dunya TV channel: "The policemen sacrificed their lives to protect the polio workers."
Pakistan and neighbouring Afghanistan are the only two countries in the world where polio remains endemic.
At least 89 people, including vaccination workers and policemen have been killed in such attacks since July 2012, according to United Nations figures and media reports.
Government officials in Karachi said the immunisation drive would be suspended while the violence was investigated.