Philippe Lazzarini of the UN Agency for Palestinian Refugees said that since Israel's Rafah operation began, there had been a massive movement of people.

"800,000 people are on the road having been forced to flee since the Israeli occupation forces started the military operation in the area on 6 May", the UNRWA chief said on X.

He said people were fleeing to areas without water supplies or adequate sanitation.

Aid groups say Israel's Rafah incursion, launched despite overwhelming international opposition and as mediators were hoping for a breakthrough in stalled truce talks, has worsened an already dire humanitarian crisis.

With key land crossings closed or operating at limited capacity because of the fighting, some aid began entering Gaza via a temporary US-built floating pier.

The Israeli army said 310 pallets began moving ashore in "the first entry of humanitarian aid through the floating pier".

Satellite pictures showed more than a dozen trucks lining up Saturday on its approach road.

In the coming days, around 500 tonnes of aid are expected to be delivered via the pier, according to US Central Command.

But UN agencies and humanitarian aid groups have warned sea or air deliveries cannot replace more efficient truck convoys into Gaza, where the UN has repeatedly warned of looming famine.

The Rafah crossing, a vital conduit for humanitarian aid, has been closed since Israel launched its assault in the city.

Meanwhile, Israel said it killed two senior Islamic Jihad fighters in air strikes in the northern West Bank and in Rafah.

The World Health Organization has received no medical supplies in Gaza since the Rafah operation began, spokesman Tarik Jasarevic said Friday.