The US last week paused a bomb shipment for Israel over concerns it was going ahead with a major ground operation in the southern Gaza city of Rafah, a senior US administration official says.

The shipment consisted of 1,800 2,000lb (907kg) bombs and 1,700 500lb bombs, the official told CBS News, the BBC's media partner in the US.

Israel has not "fully addressed" US concerns over humanitarian needs of civilians in Rafah, the official says.

Israel made no immediate comment.

Overnight, there were further Israeli air strikes in the Gaza Strip, hours after Israeli forces backed by tanks took control of the Palestinians side of the key Rafah crossing on the border with Egypt.

The Israeli bombardment was particularly intense around Rafah. Local medics said seven members of one family were killed in one strike.

Rafah has been a key entry point for aid and the only exit for people able to flee since the start of the war between Israel and Hamas last October.

The crossing remained closed on Wednesday morning, but the Israeli military said it was reopening the nearby Kerem Shalom crossing, which had been closed for four days because of Hamas rocket fire.

On Monday, the Israeli military ordered tens of thousands of civilians to begin evacuating nearby eastern parts of Rafah city, ahead of what it called a "limited" operation to eliminate Hamas fighters and dismantle infrastructure.

Meanwhile, efforts continue to reach a ceasefire, alongside the release of Israeli hostages and Palestinian prisoners. In Cairo, delegations from Israel and Hamas are due to resume negotiations through mediators.

"The US 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," the senior US administration official said on Tuesday.

"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.

"Those discussions are ongoing and have not fully addressed our concerns. 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.

"As a result of that review, we have paused one shipment of weapons last week. It consists of 1,800 2,000lb bombs and 1,700 500lb bombs," the unnamed official added.

"We are especially focused on the end-use of the 2,000lb bombs and the impact they could have in dense urban settings as we have seen in other parts of Gaza. We have not made a final determination on how to proceed with this shipment."

The official also said that "for certain other cases at the State Department, including JDAM [Joint Direct Attack Munition] kits, we are continuing the review. None of these cases involve imminent transfers - they are about future transfers".

The official stressed that the shipments were unrelated to last month's landmark $17bn military aid package, but had been drawn from "previously appropriated funds".The larger 2,000lb bombs are most likely to be Mk-84s or possibly BLU-109s - or both.

The former is a cheap, general purpose munition and the latter a penetration bomb designed for use against hardened or underground targets. Both can be fitted with JDAM kits that deliver precision capability using satellite navigation. Laser guidance kits can also be fitted.

These bombs can be made to be very accurate, down to just a few metres. But in a dense, urban environment like Gaza the risk of so-called "collateral damage" is high. And that is where the concern lies. The smaller 500lb bombs can also be fitted with guidance units dropped from jets.

We do not know exactly how Israel uses these weapons, but media posts from the Israeli Air Force frequently show F-16 and F-15 jets loaded with JDAMs for strikes.

It is worth remembering that such weapons would not just be used in Gaza but also targets in southern Lebanon belonging to the Iran-backed group Hezbollah, which has been involved in almost daily cross-border exchanges of fire with Israeli forces since the start of the Gaza war.

The weapons being held back by the US are related to a future delivery, so it is unlikely to have any immediate impact. But given the rate at which Israel is bombing it will likely affect future strikes fairly soon.

It is a clear message from a Washington growing increasingly concerned about Israel's campaign in Gaza.

Israel launched the campaign to destroy Hamas in response to the group's cross-border attack on southern Israel on 7 October, during which about 1,200 people were killed and 252 others were taken hostage.

More than 34,780 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.

A deal agreed in November saw Hamas release 105 hostages in return for a week-long ceasefire and some 240 Palestinian prisoners in Israeli jails. Israel says 128 hostages are unaccounted for, 36 of whom are presumed dead.