The United Nations held a ceremony Friday to mark the fourth anniversary of the deadly bombing of U.N. headquarters in Baghdad. Twenty two people were killed in the August 19 attack, and more than 150 others were wounded, leading the U.N. to substantially reduce its mission in Iraq. VOA's Suzanne Presto reports from the United Nations bureau in New York.

Behind the U.N. singers at the organization's headquarters, sunlight filtered through the Peace Window, a brilliant blue stained-glass work by the late Marc Chagall.

U.N. officials, staffers, loved ones of the victims and survivors gathered before a memorial plaque honoring those killed in the 2003 attack.

Nearby, the torn U.N. flag that once flew over the organization's Baghdad office is mounted on the wall.

Survivors laid a wreath of violet and yellow flowers before the plaque after victims' names were read out loud.

U.N. Secretary General Ban Ki-moon says the August 19 attack was one of the U.N.'s "darkest days."

"Four years on, our hearts remain heavy," said the U.N. chief. "We have lost colleagues before in the line of duty. But this was the first time the United Nations was deliberately targeted on such a massive scale."

Mr. Ban says the attack shattered any illusion that U.N. ideals and impartiality would permit the body to escape violence in Iraq.

Still, he said, the U.N.'s commitment to peace remains unchanged.

"Today, those very ideals, the same resolve, guide our work for peace whether in Darfur or in Delhi, or in Beirut or in Baghdad," siad Mr. Ban.

Mr. Ban says such a commitment is evident in the U.N. plan to expand its role in Iraq through the United Nations Assistance Mission for Iraq, or UNAMI. He says such work honors those who were killed in the terrorist attack, including top U.N. envoy Sergio Vieira de Mello.

"The Security Council's recent decision to renew and strengthen UNAMI's mandate is an opportunity to carry forward the work of Sergio Vieira de Mello and his colleagues," he said. "Yet I understand the fears and concerns some staff may have about any expansion. That is why I affirm to you today that any such measure remains strictly subject to conditions on the ground. Your safety is and always will be a a paramount concern."

Depending on the security situation, the U.N. Mission in Iraq is expected to increase from 55 to 95 international employees. The organization will play a larger role in brokering political dialogue inside Iraq and winning support from Iraq's neighbors for the country's security.

A U.N. spokeswoman Friday said an investigation into the August 2003 bombing is complete. She says the report identifies the attackers and explains how the bombing was carried out. She adds that findings will be made public after the victims' families are informed.