The World Health Organization (WHO) on Tuesday said Israel should let it stock medical supplies to deal with a "catastrophic" health situation in Gaza before it seizes control of Gaza City.

Israel has said its military would "take control" of Gaza City in a plan approved by Prime Minister Benjamin Netanyahu's security cabinet that sparked a wave of global criticism.

"We want to stock up, and we all hear about 'more humanitarian supplies are allowed in' – well it's not happening yet, or it's happening at a way too low a pace," said Rik Peeperkorn, the WHO's representative in the Palestinian territories.

UN agencies warned last month that famine was unfolding in Gaza, with Israel severely restricting aid entry.

Peeperkorn said the WHO was able to bring in fewer supplies than it wanted "due to the cumbersome procedures" and products "still denied" entry – a topic of constant negotiation with the Israeli authorities.

"We want to as quickly stock up hospitals... following the news – the whole discussion about an incursion in Gaza. We currently cannot do that... We need to be able to get all essential medicines and medical supplies in," he said.

Peeperkorn said only 50 percent of hospitals and 38 percent of primary health care centres were functioning, and that too partially.

"The overall health situation remains catastrophic," he said. "Hunger and malnutrition continue to ravage Gaza".

Meanwhile, the European Union, Britain and Japan called for urgent action to stop the famine there.

"The humanitarian suffering in Gaza has reached unimaginable levels. Famine is unfolding before our eyes," a joint statement signed by the EU's top diplomat and foreign ministers from 24 countries including Canada and Australia. (AFP)