United Nations Secretary General Kofi Annan has fired a security chief and demoted another senior staffer following a highly critical report by an external panel, which faulted several top officials for events leading to deadly bombing of world body headquarters in Baghdad on August 19 last year, which killed 22 people.

Annan, however rejected the resignation of his deputy Louise Frechette, a Canadian, who headed the steering group, which advised Annan to send senior staff members to work in Iraq despite unstable security situation following the US-led military action.

Two officials responsible for security on the ground in Baghdad came in for highly critical comments and were charged with misconduct. They would face disciplinary proceedings.

UN Security Coordinator Tun Myat of Myanmar on paid leave since November last was asked to step down as the report said he 'appeared to be oblivious to the developing crisis'.

Annan rejected Frechette's offer to resign but sent a critical letter to her expressing 'disappointment and regret' over security flaws, Chief UN spokesman Fred Eckhard said.

The report faulted the Group of failing to ask 'some searching questions' about the security before concluding that the staff could be sent to Baghdad.

The security officials, the report said, 'appeared to be blinded by the conviction that UN personnel and installation would not become target of attack, despite clear warnings to the contrary'.

They did not take measures to improve the security at the headquarters even after they became aware of the risk.

The report also faulted the UN for not sending a team to assess the situation before allowing the staff members to go in.

It charged the two officials responsible for the security on the ground in Baghdad with 'dereliction of duty' and 'lethargy bordering on gross negligence', saying that they failed even to ask for or install blast resistant shield on windows of the Canal Hotel where the headquarters was located.

The two, Boulos Paul Aghadjanian of Jordan and Pa MomoDou Sinyan of Gambia, have been charged with misconduct and are facing disciplinary proceedings.

The charges assume significance as 90 per cent of 150 people wounded had suffered injures from flying glass.

Twenty-two people, including UN top envoy in Iraq Sergio Vieira de Mello, were killed in the suicide bombing, which led to the withdrawal of entire UN staff from Baghdad and a through review of security procedures.

A senior official, Assistant Secretary General Ramiro Lopes da Silva of Portugal, who was security coordinator in Baghdad at the time of bombing, has been demoted and sent back to his previous posting in the World Food Programme, which does not involve security duties.

Eckhard said Annan is determined to take all corrective measures within his authority to enhance security of the UN staff.

The report by a panel headed by former deputy high commissioner for refugees Gerald Walzer is second on the bombing. The first was by former Finnish president Martti

Ahtissari, who had identified the lapses. The Walzer report looked into the responsibilities of the officials.