Staff unions said a full 1,040 staff members, or 89.4 percent of those who cast a ballot on Thursday, voted in favour of the full-day strike.
“The results, which are overwhelmingly positive, show the extent to which UN staff have lost trust in the way in which their conditions of service, whether in Geneva or in the deep field, have been set by their employer,” Ian Richards, who heads the UN staff unions association in Geneva, told AFP.
It is unclear how many of the around 9,500 UN staff members in Geneva would participate in Friday's work stoppage, but the impact on UN operations was expected to be broad.
The Human Rights Council, which is in the midst of its main annual session, will close for the day, delaying an already jam-packed program, spokesman Rolando Gomez told AFP.
Last month, UN Geneva staff staged a two-hour work stoppage after they received their first pay slips showing a 3.5-percent salary cut, with the knowledge the cut will swell to five percent by June.
That brief strike managed to disrupt high level meetings at the rights council and the Conference on Disarmament, impacting the UN Secretary-General and a number of government ministers.
'Plans to escalate'
Ahead of Thursday's vote, the head of the UN in Geneva, Michael Moller, attempted to dissuade a new strike.
He stressed that the UN “recognises and respects your freedom of association”.
But he pointed out that UN staff were “international civil servants bound by the Staff Regulations and Rules.”
“We are all reminded that the Staff Regulations and Rules provide no basis for staff members to be absent from work because of a work stoppage or strike,” he said.
Richards slammed Moller's message as an attempt at “intimidation”, which he said had backfired.
“The feedback we received is that the intimidatory email from management backfired and swayed those who were sitting on the fence in favour of the strike,” he said, adding there could be more strikes on the horizon.
“The first strike day is tomorrow, with plans to escalate if the meeting of the International Civil Service Commission, in New York next week, does not address the pay cut,” he said, referring to a body that governs UN employees, and which has ordered deep cuts to pay and benefits for many staff around the globe.
A letter sent by the unions to UN chiefs last month charged there had been a “substantial deterioration in the employment conditions of UN staff around the world, caused by ICSC's findings, recommendations and decisions.”
UN employees are considered among the highest paid civil servants in the world, but the ICSC-mandated cuts will be painful in pricy Geneva, the unions say. Staff stationed in a number of other countries will take an even heavier blow.
According to the unions, the most recent ICSC decisions include 10-percent cuts in Bangkok and 25 percent in Tokyo.
The stoppage is part of a global campaign and strikes and other actions are being voted on elsewhere too.