Secretary-General Kofi Annan fired one senior U.N. official and demoted another Monday for failing to protect U.N. staff ahead of the August 19 bombing of U.N. headquarters in Baghdad that killed 22 people.

Acting on the findings of a scathing report detailing mistakes made by several senior officials, Annan singled out Tun Myat, the U.N. security coordinator, who was asked to resign and did so.

The report said Myat and others "appeared to be blinded by the conviction that U.N. personnel and installations would not become a target of attack, despite the clear warnings to the contrary."

The secretary-general also chastised his deputy, Louise Frechette, who chaired a steering group on Iraq when the United Nations decided last May that U.N. staff could go back into the country after the U.S.-led war. She submitted her resignation but Annan refused to accept it, U.N. spokesman Fred Eckhard said.

"The secretary-general, taking into account the collective nature of the failures attributable to the Steering Group on Iraq as a whole, declined to accept the resignation," Eckhard said.

The action appeared to be unprecedented at the United Nations, where senior leaders are almost never rebuked in such a public fashion. But the bombings were extraordinarily traumatic for U.N. staff, who refer to the tragedy as "our September 11."

The investigation into the United Nations' handling of security was a demand by U.N. staff, many of whom were close to victims of the bombing.

The U.N. staff union said Annan's reprimands did not go nearly far enough. Both da Silva and Myat had stepped down temporarily late last year while independent experts assessed responsibility for the security lapses, and Myat is expected to keep his pension.

"You have 22 people dead and for the most part, the secretary-general lets people keep their jobs or retire with their pensions," said U.N. union representative Guy Candusso. "Considering the gross negligence and the lapses of security, this does not go wide enough or far enough to hold people accountable."

Equally as upsetting for thousands of U.N. personnel was the feeling that the U.N.'s most coveted asset -- immunity in hotspots _ had been lost by going into Iraq, unprotected and at the mercy of the occupation authorities.