Last year was one of the deadliest ever for U.N. personnel, with 42 civilian staff and peacekeeping troops killed in acts of violence, the world body's staff union said on Wednesday.

The worst incident was on December 11, when 17 staff members -- 14 of them Algerians -- were among at least 37 people killed in two car bomb attacks in Algiers, one of them apparently targeting U.N. offices. Al Qaeda's North African wing claimed responsibility.

On June 24, an unclaimed bombing near the south Lebanese town of Khiyam killed three Spanish and three Colombian peacekeeping soldiers on patrol for the U.N. Interim Force in Lebanon (UNIFIL).

A statement by the staff union said that for 2007 as a whole at least 33 civilians and nine peacekeeping soldiers were killed. Apart from Algeria and Lebanon, the incidents occurred in Afghanistan, Chad, Sudan, Uganda and the Gaza Strip.

Guy Candusso, secretary of the union's staff committee, said the only higher toll in recent years was in 1994, when 64 U.N. personnel died violently, mainly Rwandans caught up in the genocide of Tutsis and moderate Hutus by Hutu extremists.

The worldwide figure for last year was 22.

Candusso said he believed the toll in Algiers was the highest of any single incident involving U.N. civilian staff. The bombing of the U.N. offices in Baghdad in 2003 killed 22 people, but seven of those were visitors.

Staff union president Stephen Kisambira called on U.N. members to punish those guilty of killing U.N. employees.

"Those responsible for such heinous acts must be sought and brought to justice by member states, who are responsible for national security," he said. "Very seldom are perpetrators prosecuted, perpetuating the climate of impunity."

The union has opposed U.N. plans to increase staffing in Iraq, arguing that conditions there are too unsafe.