UNITED NATIONS (AFP) - Secretary-General Ban Ki Moon said on Monday that the UN has learned from an attack in Baghdad that killed 22 staff members a decade ago.
But some survivors present at the remembrance ceremony criticised the global body's handling of the crisis.
"We are changing the way we operate around the world," Mr Ban said, adding the UN has tried to boost mission security and care for employees in dangerous situations. "We also recognise our obligations to stand side by side with families of the victims in their long journey to healing."
On Aug 19, 2003, a suicide bomber detonated an explosives-rigged truck at the Canal Hotel in the Iraqi capital, smashing a corner of the building and killing Brazilian UN envoy Sergio Vieira de Mello and 21 others.
To mark the somber anniversary and pay tribute to the victims, UN officials and survivors marked a minute of silence.
"Today the attackers who target us have grown more sophisticated, more brazen and better armed," Mr Ban said at the remembrance ceremony held at United Nations headquarters in New York.
But survivor Laura Dolci-Kannan said many who made it through the attack alive have left the service "due to the organisation's inability to reintegrate them with dignity."
The UN still has "a long way to go to fully acknowledge and deal with the physical and psychological damages suffered in the line of duty," she added.
Mr Ian Richards, president of the UN's Staff Coordinating Council in Geneva, a union for employees, said the body must implement an "independent judicial corner" to probe attacks, as well as provide better medical support and aid to educate orphans.
He also urged the use of fewer contractors and more UN security guards to protect missions.
"The UN flag is now a target instead of a shield, that means we have to change how we go about things," Mr Richards said.
During the last 10 months, 30 other UN employees have died on mission, particularly in an attack in Mogadishu, Mr Ban noted.