The World Health Organization (WHO) Thursday suspended its operations in Pakistan's Balochistan after unidentified gunmen killed four polio vaccination workers in Quetta city Wednesday.
The decision to suspend the operation was made owing to looming threats to polio workers in Balochistan, Dawn online reported, citing a source.
"We have suspended all operations in Balochistan," the source said.
WHO and the Unicef have been assisting the Balochistan government in polio eradication for more than 20 years.
In the meantime, Unicef has also scaled down its activities in Balochistan because of security threats to its staff.
Security around UN offices in Balochistan was tightened after the attack.