JERUSALEM (Reuters) -The Israeli army released drone footage showing armed men standing next to U.N. marked vehicles at a United Nations compound in the southern Gaza city of Rafah, and called on the U.N. to investigate.

An UNRWA spokesperson said the agency could not verify the authenticity or content of the video nor the exact timing or location, but it was likely that the video showed an UNRWA warehouse in Rafah that staff left in the week of May 6.

She said flour and some U.N. marked vehicles were left in the facility when it was abandoned following Israeli evacuation orders issued prior to the seizure by Israeli forces of the Palestinian side of the Rafah crossing into Egypt.

"UNRWA condemns the use of UN facilities by any party to the conflict for military/fighting purposes," UNRWA spokesperson Juliette Touma said in a statement, calling on all parties to respect the neutrality of UN installations.

"Under no circumstances should anyone have or use weapons in a UN facility," she said.

An IDF statement said that on Saturday, troops had identified fighters in the central logistics compound of the U.N. Palestinian relief agency UNRWA east of Rafah, where the Israeli military has been operating for more than a week.

Reuters located the footage by matching nearby buildings, poles, railings, tanks on a roof and greenery to satellite and file images, but was not able to verify the date it was filmed or the identity of the armed men.

UNRWA has been the target of fierce criticism by Israel, which accuses the agency of cooperating with the Islamist movement Hamas in Gaza and has called for it to be disbanded.

The agency, set up to help Palestinian refugees displaced during the war that broke out around the time of the creation of the state of Israel in 1948, strongly denies the accusations.

Israeli military spokesman Rear Admiral Daniel Hagari said the army had forwarded the footage to "senior members of the international community" and called on the U.N. to investigate the connection between UNRWA logistics centres and what he described as "Hamas operatives" near their vehicles.

Hamas rejected the suggestion that the men were fighters as "false allegations and lies". "This is a police force tasked with securing aid centers against acts of theft and looting," senior Hamas official Sami Abu Zuhri told Reuters.

Israeli criticism of UNRWA has intensified at a time of growing international pressure on Israel to step up relief supplies into Gaza to ease a humanitarian crisis that threatens severe hunger to hundreds of thousands displaced by the war.

Israel says it is ready to allow unlimited humanitarian supplies into Gaza and blames U.N. relief agencies and other international bodies for failing to distribute the aid properly.

U.N. relief agencies say aid distribution in Gaza has been severely curtailed by fighting and have accused Israel of restricting access to the enclave despite famine warnings.

UNRWA said 38 of its installations were impacted by the recent Israeli operation, including 21 affected by the evacuation orders in Rafah.

(Reporting by James Mackenzie; editing by Philippa Fletcher, Editing by William Maclean)