The Israel Defence Forces (IDF) says it has discovered a tunnel network 700 hundred metres long and 18 metres deep, which runs partly under the Gaza headquarters of the United Nations Relief and Works Agency for Palestinian Refugees in the Near East (UNRWA).

Army engineers took reporters from foreign news outlets through the passages, according to Reuters.

Reporters entered a shaft next to a school on the periphery of the U.N. compound, descending to the concrete-lined tunnel. Twenty minutes of walking through the stiflingly hot, narrow and occasionally winding passage brought them to beneath UNRWA Headquarters.

The tunnel revealed side rooms with an office, steel safes, and a toilet. One large chamber was packed with computer servers, another with industrial battery stacks.

The IDF commander said: ‘Everything is conducted from here. All the energy for the tunnels, which you walked through, are powered from here.

‘This is one of the central commands of the … Hamas intelligence units, where they commanded most of the combat.’

Hamas appeared to have evacuated the tunnel, preemptively cutting off communications cables that, in an above-ground part of the tour, the Israeli commander showed running through the floor of the UNRWA Headquarters’ basement.

UNRWA said it vacated the headquarters on 12 October, five days after the war began, and was therefore ‘unable to confirm or otherwise comment’.

The UN agency said in its statement: ‘UNRWA … does not have the military and security expertise nor the capacity to undertake military inspections of what is or might be under its premises.

‘In the past, whenever (a) suspicious cavity was found close to or under UNRWA premises, protest letters were promptly filed to parties to the conflict, including both the de facto authorities in Gaza (Hamas) and the Israeli authorities.’

A lack of cellphone reception in the tunnel made geolocating it as under UNRWA Headquarters impossible.