WASHINGTON - US president Joe Biden’s administration halted a shipment of bombs to Israel amid concerns that Israeli forces were going to launch a major ground offensive in Rafah, an official from the Biden administration revealed.

Israel was set to receive 1,800 bombs weighing around 2,000lbs (907kg) and 1,700 bombs weighing 500lbs (227kg) last week, the White House administration official said, speaking on condition of anonymity.

Officials in Israel have not “fully addressed” the concerns of humanitarian needs of civilians in Rafah as flagged by Washington, the official said.

Despite pleas from its closest allies to hold off, Israel moved its tanks into east Rafah and captured the border crossing overnight on Tuesday, in what it called a “limited” operation meant to kill fighters and dismantle infrastructure used by Hamas militants.

Israeli prime minister Benjamin Netanyahu said it was an “important step” toward dismantling Hamas. UN officials have issued a stark warning, saying Gaza has entered the “darkest days of a seven-month nightmare”. It stated that vital aid was being “choked off” after Israeli forces and tanks seized control of the main aid crossing in Rafah.

The US official said that the Biden administration’s position “has been that Israel should not launch a major ground operation in Rafah, where more than a million people are sheltering with nowhere else to go”.

"We have been engaging in a dialogue with Israel in our Strategic Consultative Group format on how they will meet the humanitarian needs of civilians in Rafah, and how to operate differently against Hamas there than they have elsewhere in Gaza,” the official said.

The official said discussions were still continuing but “as Israeli leaders seemed to approach a decision point on such an operation, we began to carefully review proposed transfers of particular weapons to Israel that might be used in Rafah”.

"As a result of that review, we have paused one shipment of weapons last week. It consists of 1,800 2,000lbs bombs and 1,700 500lbs bombs. We are especially focused on the end-use of the 2,000-lb bombs and the impact they could have in dense urban settings as we have seen in other parts of Gaza,” the official said.

The official said White House has not made a “final determination on how to proceed with this shipment”.

The White House and Pentagon declined comment to Reuters. Without addressing whether there had been a holdup in arms shipments, White House press secretary Karine Jean-Pierre reaffirmed that Washington’s commitment to Israel’s security was “ironclad”.

This comes just hours after Hamas announced it had accepted an Egyptian-Qatari mediated ceasefire and hostage proposal. Mr Netanyahu said that the proposal fell far short of Israel’s “essential” demands. Negotiations for a truce in Cairo are ongoing – with Israel saying it had sent officials to the Egyptian capital.

Israel has not demonstrated to the UK how it will safeguard civilians if it mounts a full-scale assault on Rafah, Downing Street said.

Prime minister Rishi Sunak said he was “deeply concerned” about the potential humanitarian cost of an offensive around the city in southern Gaza which has become a refuge for Palestinians forced out of other areas in the war-ravaged territory.

The UK urged both sides in the Israel-Hamas conflict to focus on negotiations to end the bloodshed.