The United States halted a shipment of bombs to Israel last week after it failed to address Washington's concerns over plans to invade the southern Gaza city of Rafah, a senior US official said Tuesday.

"We have paused one shipment of weapons last week. It consists of 1,800 2,000-lb (907 kg) bombs and 1,700 500-lb (226 kg) bombs," the senior official in President Joe Biden's administration said on condition of anonymity.

"We have not made a final determination on how to proceed with this shipment," the official added.

Biden's administration made the decision when it appeared Israel was on the verge of a major ground operation into Rafah, which Washington has strongly opposed.

Israeli and US officials had been discussing alternatives but "those discussions are ongoing and have not fully addressed our concerns," the senior US official said.

"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. This began in April."

The US official said Washington was "especially focused" on the use of the heaviest 2,000-lb bombs "and the impact they could have in dense urban settings as we have seen in other parts of Gaza."

The US State Department is still reviewing other weapons transfers, including the use of precision bomb kits known as JDAMs, added the official.

Israel sent tanks into Rafah on Tuesday and seized the border crossing with Egypt but the White House said earlier that Israel had promised it was a "limited operation."