Safety concerns are forcing the UN to withdraw some of its staff from Pakistan.
Amid increasing attacks from Taliban militants, some workers are being relocated to safer locations inside and outside the country.
The UN maintains the move does not mean the end of any of its projects in Pakistan.
Bomb attacks have been spreading from remote tribal areas to major cities, despite new crackdowns by the military.
The Taliban has claimed responsibility for a suicide bombing on Monday that killed 43 people in Karachi.
Also, in October, five UN staff members were killed when a suicide bomber dressed as a soldier struck a UN World Food Programme office in Islamabad.