Two more polio vaccination workers have been killed in north-western Pakistan in the latest in a string of attacks against the health workers.
A vaccination supervisor and her driver were killed and a volunteer in the disease eradication programme injured in the shooting in the Peshawar region on Wednesday.
The deaths brought to eight the number of health workers killed in this week's anti-polio drive. The three-day UN-backed drive is now over.
No group has claimed responsibility, but the Taliban have issued threats against the UN's anti-polio efforts.
The militants have accused health workers of working as US spies and say the vaccine makes children sterile.
Pakistan is one of just three countries where the disease is still endemic.
Coming after five deaths on Tuesday, and one on Monday, the UN children's agency Unicef and the World Health Organisation halted work in Sindh province in the south and Khyber Pakhtunkhwa in the north-west on Tuesday.
The suspension was extended nationwide on Wednesday, the BBC reports.
The UN provides technical and financial support to employees and volunteers of the local health departments who administer the polio drops.
Reuters news agency reported that despite the killings, the immunisation drive continued in some areas on Wednesday - although a number of local health workers refused to go out.