A former U.S. Special Forces colonel has warned that an Israeli ground invasion into Gaza "could happen any day now."

American President Joe Biden has advised Israel to delay a ground invasion of Gaza, hoping to buy time for hostage negotiations and to allow more humanitarian aid in to reach Palestinians in the sealed-off enclave.

Two weeks into the escalation of conflict with Hamas, the much-anticipated ground invasion of Gaza has yet to materialize.

But retired U.S. Special Forces colonel Liam Collins, co-author of the forthcoming book Understanding Urban Warfare, says while the incursion so far been delayed it is only a matter of time before Israel makes a more sustained entry into Gaza.

"It takes time for them," he said. "They have a war plan that's on the shelf but they really have to refine that for the specific operation based on specific intelligence. So that's what they're doing right now, preparing for that ground invasion into the Gaza, which could happen any day now."

Israeli Prime Minister Benjamin Netanyahu had reportedly told U.S. President Joe Biden: "We have to go in" and a ground assault appeared imminent after the Israel Defense Forces sent 100,000 troops to the Gaza border during the first week of the escalation in tensions.

A military spokesman said on Saturday Israel will step up its strikes on Gaza to increase pressure on Hamas but it is believed the U.S influence is key to a delay in ground invasion, with foreign nationals and dual citizens at risk.

"Part of it is right," added Collins. "These dozens of hostages, many of them aren't just Israeli, but they're dual citizens or foreigners that are being held. And obviously they're going to be put at greater risk with any kind of ground invasion."

Despite this, Collins agrees that there may be no stopping a ground invasion into Gaza, which now seems inevitable.

"I would think so," he agreed. "I would think so. I mean, if you look in 2009 and 2014, based off of significantly smaller attacks or justifications into Israel, they launched ground invasions into Gaza that took 14 and 19 days. 

"(They will aim to) degrade Hamas' capability so that they aren't able to conduct a large attack like this again, where they killed hundreds or thousands of Israeli and foreign citizens that were civilians, that almost never can be done by air alone without really, really good intelligence. And so that almost to do that requires a ground invasion to go out there and hit the logistic points."

Collins insisted Hamas cannot be fully dismantled by Israel but can be set back in their offensive. "They can be degraded. They can't be destroyed. As long as the underlying roots of the conflict aren't being addressed, there's going to be some kind of resistance," Collins said. "But what Israel wants to do is degrade it to such a level that they're not capable of conducting a large cross-border raid like they conducted a couple of weeks ago."

Meanwhile, an elderly Israeli hostage who was released by Hamas overnight said she had been beaten by the militants when she was abducted and taken to Gaza on October 7 but was then treated well during her two-week captivity in the Palestinian enclave.

Yocheved Lifshitz, 85, one of two women freed late on Monday, leaving around 220 hostages still in the hands of Hamas, including both of their husbands, said: "I've been through hell. They stormed into our homes. They beat people. They kidnapped others, the old and the young without distinction."

At least 5,791 Palestinians have been killed since October 7, including 2,360 children, Gaza's health ministry said in a statement on Tuesday, with 704 Palestinians killed in the last 24 hours in Gaza in Israeli strikes.

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Twelve British nationals were killed in the attacks by Hamas on Israel and another five are still missing, a spokesperson for British Prime Minister Rishi Sunak said.

Doctors in Gaza say patients arriving at hospitals are showing signs of disease caused by overcrowding and poor sanitation after more than 1.4 million people fled their homes for temporary shelters under Israel's heaviest-ever bombardment.

"The crowding of civilians and the fact that most schools used as shelters are housing lots of people, it's a prime breeding ground for disease to spread," said Nahed Abu Taaema, a public health doctor at Nasser Hospital in Khan Younis.

French President Emmanuel Macron proposed on Tuesday an international coalition fighting against Islamic State in Iraq and Syria be widened to include the fight against the Palestinian militant group Hamas in Gaza.

Israel's military dropped leaflets in Gaza on Tuesday, urging Palestinians to give them information about hostages being held by Hamas and offering them protection and a reward.

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