The solemn chamber was transformed for the occasion on Friday, with an improvised stage and a gigantic arching screen.

Clad in a white dress with sequins, the winner of 16 Grammy Awards sang one of her hits, "I was here," before images of floods and rescuers digging through rubble after an earthquake.

The video, which the singer offered as a donation to the UN, will be included in a campaign broadcast on the Internet at www.whd-iwashere.org, illustrating the work of humanitarian organizations around the world. The video will be accompanied by the testimonies of millions of volunteers.

"We all see the headlines and with think: 'What can I really do to help?' World Humanitarian Day is an opportunity for all of us to work together to make a difference," Beyonce said in a release.

World Humanitarian Day was established in 2008 to commemorate the attack on August 19, 2003 against the UN headquarters in Baghdad, which claimed the lives of 22 UN workers, including a UN special envoy to Iraq, Sergio Vieira de Mello. His son, Laurent Vieira de Mello, was present at the event Friday evening, as well as other personalities involved in humanitarian aid and entertainment.