Flags flew at half-mast at United Nations compounds across the globe on Monday, as staff observed a minute's silence in memory of colleagues killed in Gaza during the Israel-Hamas conflict.

The blue and white UN flag was lowered at 9:30 am local time at offices in Bangkok, Tokyo and Beijing, a day after the world body reported "a significant number of deaths and injuries" in strikes on a facility in Gaza.

In Geneva, the second-largest UN headquarters after New York, the UN flag flew at half-mast and none of the other flags of the 193 member countries were hoisted along the main alley of the compound. Staff were also invited to hold a "private" minute of silence, spokesman Rolando Gomez said.

Events were also held in Kathmandu and Kabul, where the UN Secretary-General's Special Representative for Afghanistan Roza Otunbayeva led about 250 people in observing the minute's silence.

The UN agency for supporting Palestinians (UNRWA) announced on Friday that more than 100 of its employees had died in the Gaza Strip since the start of the war.

Israel has been bombing targets across the Gaza Strip since Hamas fighters carried out an October 7 attack on southern Israeli communities, the deadliest in the country's history.

About 1,200 people, mostly civilians, were killed in the Hamas attacks and around 240 people taken hostage, according to Israeli officials.

More than 11,000 people, most of them civilians and many of them children, have been killed in Gaza in retaliatory strikes by Israel, according to the Hamas-run health ministry in the territory.