US President Donald Trump's envoy met Israeli Prime Minister Benjamin Netanyahu on Thursday ahead of a visit to inspect aid distribution in Gaza, as a deadly food crisis drove mounting international pressure for a ceasefire.

Steve Witkoff, who has been involved in months of stalled negotiations for a ceasefire and hostage release deal, met Netanyahu shortly after his arrival, the Israeli leader's office said.

He is to visit Gaza on Friday, the White House said.

White House press secretary Karoline Leavitt told reporters that Witkoff, who visited Gaza in January, would inspect "distribution sites and secure a plan to deliver more food and meet with local Gazans to hear firsthand about this dire situation on the ground".

German Foreign Minister Johann Wadephul also met Netanyahu in Jerusalem, and afterwards declared: "The humanitarian disaster in Gaza is beyond imagination.

"Here, the Israeli government must act quickly, safely and effectively to provide humanitarian and medical aid to prevent mass starvation from becoming a reality," he said.

"I have the impression that this has been understood today."

In an example of the deadly problems facing aid efforts in Gaza, the territory's civil defence agency said that at least 58 Palestinians were killed late on Wednesday when Israeli forces opened fire on a crowd attempting to block an aid convoy.

The Israeli military said troops had fired "warning shots" as Gazans gathered around the aid trucks. An AFP correspondent saw stacks of bullet-riddled corpses in Gaza City's Al-Shifa Hospital.

Jameel Ashour, who lost a relative in the shooting, told AFP at the overflowing morgue that Israeli troops opened fire after "people saw thieves stealing and dropping food and the hungry crowd rushed in hopes of getting some".

Witkoff has been the top US representative in indirect negotiations between Israel and Hamas but talks in Doha broke down last week and Israel and the United States recalled their delegations.

Israel is under mounting international pressure to agree a ceasefire and allow the world to flood Gaza with food, with Canada and Portugal the latest Western governments to announce plans to recognise a Palestinian state.

Trump criticised Canada's decision and, in a post on his Truth Social network, placed the blame for the crisis squarely on Palestinian militant group Hamas.

"The fastest way to end the Humanitarian Crises in Gaza is for Hamas to SURRENDER AND RELEASE THE HOSTAGES!!!" declared Trump, one of Israel's staunchest international supporters.

Earlier this week, however, the US president contradicted Netanyahu's insistence that reports of hunger in Gaza were exaggerated, warning that the territory faces "real starvation". (AFP)