GENEVA : Angered by "unfair" pay cuts, UN staff in Geneva are planning a half-day strike next week, as dozens of ministers and other dignitaries attend high-level events at the organisation's European headquarters.

"We have tried other forms of protest before, to no avail... They have left us no choice," Ian Richards, who heads the UN staff unions association in Geneva, told AFP Sunday.

He said it remained unclear how many of some 9,500 UN staff members in Geneva would participate in Tuesday's work stoppage, or what impact it would have, pointing out that "this is not like a bus company where the buses just stop."

"But we certainly expect this to have an impact," Richards said.

The half-day work stoppage will come during what is arguably one of the busiest weeks of the year at the UN in Geneva, with around 100 heads of state, government ministers and country representatives from around the world set to attend the main annual sessions of the UN's top human rights and disarmament bodies.

According to a letter sent to all UN agency chiefs late last week, Tuesday will mark only "a first day of action, (and will) be followed by others."

It complained of a "substantial deterioration in the employment conditions of UN staff around the world," and warned that "the reputation of the UN as a leading employer that treats its staff with respect and fairness has been tarnished."

The letter, sent by the unions and representatives of civil servants working for the UN, went out as staff received their first pay slips showing a 3.5-percent salary cut, and with the knowledge that the cut will swell to five percent by June, Richards said.