By Jibran Ahmad
PESHAWAR, Pakistan | Wed Dec 19, 2012 8:59am EST
(Reuters) - Three workers in a polio eradication campaign were shot in Pakistan on Wednesday, and two of them were killed, the latest in an unprecedented string of attacks over the past three days that has partially halted the U.N.-backed campaign.
The United Nations in Pakistan has pulled all staff involved in the campaign off the streets, spokesman Michael Coleman said.
The government said immunization was continuing in some areas without U.N. support although many workers refused to go out. Women health workers held protests in the southern city of Karachi and in the capital, Islamabad.
Wednesday saw four separate attacks, all in the north. In the district of Charsadda, men on motorbikes shot dead a woman and her driver, police and health officials said.