Israeli forces massed tanks and opened fire close to built-up areas of Rafah on Thursday, residents said after US President Joe Biden vowed to withhold weapons from Israel if its forces launch a major invasion of the southern Gaza city.

As ceasefire talks continued in Cairo, Palestinian militant groups Hamas and Islamic Jihad said their fighters struck Israeli forces on the eastern outskirts of Rafah, firing anti-tank rockets and mortars at Israeli positions.

Residents and medics in Rafah, the only major urban area in Gaza not yet invaded by Israeli ground forces, said Israeli tank fire killed three people and wounded others near a mosque in the eastern neighbourhood of Brazil.

On the city’s eastern edge, residents said a helicopter opened fire, while drones hovered above houses in several areas, some close to rooftops.

Israel says Hamas militants are hiding in Rafah, where hundreds of thousands of Palestinians have sought refuge after fleeing combat elsewhere in Gaza, and it needs to eliminate them for its own security.

CIA director William Burns, back in the Egyptian capital after talks in Jerusalem, resumed meetings on Thursday with mediators trying to secure a ceasefire, two Egyptian security sources said.

Biden, who says Israel has not produced a convincing plan to safeguard civilians in Rafah, issued his starkest warning yet against a full ground invasion.

“I made it clear that if they go into Rafah, ... I’m not supplying the weapons,” Biden told CNN in an interview on Wednesday.

Israeli tanks seized the Gaza side of the Rafah border crossing with Egypt on Tuesday, cutting off a vital aid route and forcing 80,000 people to flee the city this week, according to the UN.

“The toll on these families is unbearable. Nowhere is safe,” the UN agency for Palestinian refugees said in a post on X. An Israeli military statement on Gaza operations on Thursday morning did not refer to Rafah.

The US is by far the biggest supplier of weapons to Israel, and it accelerated deliveries after the Hamas attacks.