The death toll from attacks on volunteers vaccinating children in Pakistan against polio has risen to nine, officials said.
Hilal Khan, 20, died a day after he was shot in the head in the north-western city of Peshawar, said health official Janbaz Afridi.
Since Monday, gunmen have launched attacks across Pakistan on teams vaccinating children against polio in a UN-backed programme jointly conducted with the Pakistani government. Six women were among the nine people killed.
The UN World Health Organisation suspended the drive until a government investigation was completed.
UN Secretary-General Ban Ki-moon called the killings "cruel, senseless and inexcusable". Speaking at his year-end news conference, Mr Ban said the victims were among thousands across Pakistan "working selflessly to achieve the historic goal of polio eradication".
The suspension of the vaccinations was a grave blow to efforts to bring an end to the scourge of polio in Pakistan, one of only three countries where the crippling disease is endemic.
Azmat Abbas, with Unicef in Pakistan, said field staff would resume their work when they have a secure working environment. Unicef spokeswoman Sarah Crowe said: "This is undoubtedly a tragic setback, but the campaign to eradicate polio will and must continue."
However, local officials in the eastern city of Lahore continued the vaccination under police escort, and extended the campaign with a two-day follow-up.
Deputy Commissioner Noorul Amin Mengal said about 6,000 Pakistani government health workers were escorted by 3,000 police as they fanned out across the city. He said: "It would have been an easy thing for us to do to stop the campaign. That would have been devastating."
No-one has claimed responsibility for the attacks but some Islamic militants accuse health workers of acting as spies for the United States and claim that the vaccine makes children sterile.