Lord Cameron has urged Israel to “stop and think seriously” before launching a ground assault on the southern city of Rafah, saying the people there had nowhere to go.

Benjamin Netanyahu has brushed aside international alarm over Israel’s plans to invade the southern enclave, where around 1 million displaced civilians are sheltering, insisting Israel’s military operations will continue until “total victory” is achieved.

On Monday the UK Foreign Secretary said Britain was “very concerned” amid reports of a ground invasion and reiterated calls for a “sustainable ceasefire”.

“We think it is impossible to see how you can fight a war amongst these people”, he said. “There’s nowhere for them to go.”

He added: “So we are very concerned about the situation and we want Israel to stop and think seriously before it takes any further action.”

Downing Street echoed Lord Cameron’s reservations, with Rishi Sunak’s official spokesman saying: “We are obviously deeply concerned about the prospect of a military offensive in Rafah.”

They declined to say whether the Prime Minister believes “total victory” over Hamas was realistic, instead doubling down on calls for a “pause in this fighting so we can get aid in and hostages out”.

It comes after an Israeli special forces rescue operation freed two Israeli-Argentine hostages held by Hamas militants in Rafah in the early hours of Monday morning, with the supporting airstrikes killing 67 people.

The US has also objected to Israel conducting military operations in the densely populated region without a credible evacuation plan.

Aid agencies say an assault on Rafah would be catastrophic. Egypt has reinforced its border with the city, saying it fears Gazans will be pushed across, never to return.

But Eylon Levy, an Israeli government spokesman, said on Monday Israel was fighting to prevent “extremism and terrorism from spiralling further in Europe” and said it expected its allies to stand by it.

Mr Levy called on UN aid agencies to help facilitate the offensive, urging them to: “Work with us to find a way.”

Last week Joe Biden called Israel’s military response in Gaza “over the top”, and also sought “urgent and specific” steps to strengthen humanitarian aid.

On Monday Josep Borrell, the EU’s foreign policy chief, urged allies of Israel, primarily the United States, to stop sending weapons to Israel, as “too many people” are being killed in Gaza.

Referring to Mr Biden’s comments, he said: “Well, if you believe that too many people are being killed, maybe you should provide less arms in order to prevent so many people ... [being] killed.”

Concerns over the country’s tactics led to a Dutch appeals court blocking the export of F-35 fighter jet parts to the country over a “clear risk of violations of international humanitarian law” in Gaza.

On Monday Britain followed the US in announcing sanctions on four “extremist Israeli settlers” accused of committing human rights abuses against Palestinians in the West Bank.

Announcing the new curbs, which comprise UK asset freezes alongside travel and visa bans, Lord Cameron said: “Israel must also take stronger action and put a stop to settler violence.”