Israeli soldiers are expected to advance into the southern city of Rafah, which borders Egypt.
One of the last remaining areas in Gaza not yet infiltrated by Israeli troops in the four months since the war began, approximately half of Gaza’s 2.3 million population is thought to be sheltering in Rafah.
In a post on X (formerly Twitter) on Saturday evening, Cameron wrote: “Deeply concerned about the prospect of a military offensive in Rafah – over half of Gaza’s population are sheltering in the area.
“The priority must be an immediate pause in the fighting to get aid in and hostages out, then progress towards a sustainable, permanent ceasefire.”
Earlier this month, Cameron also said the UK could recognise a Palestinian state while Israeli negotiations with Palestinian leaders are ongoing.
He added: “Those who say that under no circumstances should we enter Rafah are basically saying, ‘Lose the war. Keep Hamas there.’”
Israel claims Rafah is the last remaining stronghold for the Palestinian militants Hamas.
Netanyahu has called for the evacuation of people in Rafah but it is not clear where any civilians could move to, as Israeli evacuation orders cover two-thirds of Gaza.
There are fears about the general conditions in Gaza are growing, too.
The UN secretary-general Antonio Guterres called for a humanitarian ceasefire before a “gigantic tragedy” develops in Rafah last week.
Israel declared war on Hamas after the group killed an estimated 1,200 people on Israeli soil on October 7.
Israel’s subsequent siege and ground invasion of Gaza has killed more than 28,000 people, according to the local Hamas-run health ministry.
He wrote on X: “1.4 million displaced Palestinians are in Rafah, with nowhere to go. It’s the gateway for aid to Gaza.
“An Israeli offensive there would be catastrophic. Far too many civilians have already been killed or wounded.
“The fighting must stop now. We need a sustainable ceasefire.”