Updated

Finland's former president will lead an independent investigation of the security situation at U.N. headquarters in Baghdad (search) just before the August bombing that killed 22 people and injured more than 160, a U.N. spokesman said Monday.

U.N. spokesman Fred Eckhard announced the appointment of Martti Ahtisaari (search) hours after a homicide car bomber killed an Iraqi policeman and injured 19 other people outside the Baghdad headquarters.

The U.N. Staff Union (search), representing 5,000 staff members worldwide, said the latest car bombing "has highlighted yet again the unacceptable risks undertaken daily by the United Nations staff continuing to work in Iraq." It reiterated its call for the suspension of U.N. operations in Iraq and the withdrawal of all U.N. staff until the security situation there improves.

At the time of the Aug. 19 bombing, there were about 300 international staff in Baghdad and another 300 elsewhere in Iraq. Manpower then was ordered cut to a maximum of 50 essential international staffers.

The union, which had called for "a full and independent investigation to determine why adequate security was not in place" at the Baghdad headquarters, welcomed Ahtisaari's appointment.

But it questioned whether his investigation could be totally independent since Ahtisaari was selected by Secretary-General Kofi Annan. Earlier this month, the Staff Union said there were many questions about the attack that remained unanswered, including the role of senior officials and Annan's own responsibility for ensuring the safety and security of U.N. employees.

The Staff Union's committee on security wanted the U.N. General Assembly -- not Annan -- to be responsible for the investigation.

Ahtisaari has named three panel members: Ireland's deputy police commissioner Peter Fitzgerald, Finnish Army Brig. Gen. Jaakko Taneli Oksanen and Claude Bruderlein, director of the program on humanitarian policy and conflict research at Harvard University.

After the Aug. 19 bombing, which killed top U.N. envoy Sergio Vieira de Mello, the Staff Union's security committee demanded to know why so many U.N. personnel were in Baghdad despite a high-level security alert. According to U.N. officials, Baghdad has been at Phase IV security level since the end of the war -- one level below the highest.

Phase IV enables the U.N. official in charge of security to recommend to the secretary-general the evacuation of all non-essential staff.

The Staff Union said it also wanted to know whether political concerns outweighed security risks in deploying staff to Baghdad, whether staff members were properly briefed, whether minimum conditions for U.N. operations were met, and the status of insurance coverage for U.N. staff.