Staff at U.N. offices in Geneva bowed their heads as a candle was lit in memory of the 101 employees of U.N. Palestinian refugee agency (UNRWA) killed in the Israeli assault on Gaza.

"This is the highest number of aid workers killed in the history of our organisation in such a short time," said Tatiana Valovaya, Director-General of the United Nations in Geneva.

"We are gathered here today, united in this very symbolic location, to pay respect to our brave colleagues who sacrificed their lives while serving under the United Nations flag."

UNRWA has said that some staff members were killed while queuing for bread while others were killed along with their families in their homes in Israel's aerial and ground war against Hamas in response to the Oct. 7 cross-border assault by the Islamist group.

Israel blames Hamas for civilian deaths in the densely populated enclave, saying the group uses the population as human shields. Hamas denies the charge.

"I would like to say that we are really facing very challenging times for multilateralism, for the world," Valovaya said. "But the United Nations is more relevant than ever."

Established in 1949 following the first Arab-Israeli war, UNRWA provides public services including schools, healthcare and aid. Many of UNRWA's 5,000 staff working in Gaza are Palestinian refugees themselves.