UN Secretary-General Antonio Guterres observes a minute of silence in remembrance of fallen colleagues during the 2003 attack targeting the UN Assistance Mission in Iraq, at the UN headquarters in New York, Aug. 17, 2018. UN Secretary-General Antonio Guterres on Friday laid a wreath at the UN headquarters for his colleagues killed in the Aug. 19, 2003 attack in Iraq that prompted the designation of the International Humanitarian Day. (Xinhua/Li Muzi)

UNITED NATIONS, Aug. 17 (Xinhua) -- UN Secretary-General Antonio Guterres on Friday laid a wreath at UN headquarters for his colleagues killed in the Aug. 19 2003 attack in Iraq that prompted the designation of the International Humanitarian Day.

After laying the wreath and observing a minute of silence, Guterres said he was personally close to some of the 22 victims, including their leader Sergio Vieira de Mello, who lost lives in the first mass terror attack deliberately targeting the UN.

"Many of you also lost friends from across the United Nations family. This was a huge personal loss to so many of us," he said, addressing UN staff and the victims' families present at the ceremony.

UN staff have been targeted by those who want to weaken them and make them afraid to do their job, he said, adding though he is committed to improving security for all UN staff, "our work will never be free from risk."

Guterres praised his colleagues' courage to carry out their mission, saying "the blue flag of the United Nations flies high because of the brave women and men who carry it to the farthest corners of the world."

He called on UN staff to continue about their work, including going to "dangerous places with the aim of making them safer," as a best way to pay tribute to the fallen humanitarian workers, peacekeepers, and military and civilian staff, noting that their legacy is lasting and "will be ever-present in our hearts."

Aug. 19 was designated as World Humanitarian Day by the UN General Assembly in 2008 to mark the bombing that targeted the UN Assistance Mission in Iraq on Aug. 19, 2003. The blast at the Canal Hotel in Baghdad killed 22 people, including the world body's top envoy in Iraq, Sergio Vieira de Mello.

This year, the UN and its humanitarian partners have launched a "living petition," calling on world leaders to better protect civilians and aid workers.

Global citizens are asked to "sign" the petition with their self through a custom web that transforms their two-dimension photos into 3-D portraits of solidarity.

Their faces are part of an installation at UN headquarters, and will remain in place throughout the General Assembly, which begins on Sept. 18.

"The thousands of faces that make up the living petition will be on display to remind world leaders of their legal obligation to protect civilians in conflict," said Mark Lowcock, chief of UN Emergency Relief Coordinator and Humanitarian Affairs leading the petition.

According to UN figures, overall last year, 139 aid workers were killed, 102 wounded and 72 kidnapped in the line of duty, marking the fifth consecutive year in which more than 100 humanitarians lost their lives on the job. Moreover, it is the highest recorded annual death toll since 2013, when 156 humanitarians were killed.

Also in 2017, of the 42,972 people reportedly killed or injured by explosive weapons, three out of every four victims were civilians, a 38-percent increase over the previous year.