UN staff blast officials, spare Annan

But amid frustration bubbling since the deadly attack on the UN's Baghdad compound last year, the union said senior managers had "eroded the trust of staff" by repeatedly clearing top UN officials of wrongdoing.

The move came just days after Annan pardoned the head of the UN's internal oversight office, Dileep Nair, who had been targeted with allegations of harassment and favouritism.

The union resolution said the enquiry into Nair's case was "insufficient and constitutes a failure to properly investigate," and that it underlined "a lack of integrity, particularly at the higher levels of the organisation."

Union president Rosemarie Waters said Annan nevertheless had the support of the staff union, telling reporters: "He is in a very difficult job under very difficult circumstances. He is doing his best."

That public declaration of support came amid heavy media scrutiny after a leaked draft resolution called to send a vote of no confidence to Annan following a string of scandals that have plagued the UN chief in recent months.

Another top official, UN High Commissioner for Refugees Ruud Lubbers, was cleared by Annan in July after a female member of his staff complained that he had sexually harassed her.

Earlier this year, Annan declined the resignation of his deputy secretary general, Louise Frechette, after a damning report found important security lapses surrounding the August 19, 2003, bombing of the UN's Baghdad offices.

That attack killed 22 people and injured more than 100, and claimed the life of the UN's top official in Iraq at the time, Sergio Vieira de Mello.