The Government has organised flights to help British nationals leave Israel.
The first flight is expected to leave the Israeli city of Tel Aviv on Thursday, the Foreign Office said, with further flights planned in the coming days subject to the security situation.
The UK has also sent a rapid deployment team to assist British citizens on the ground.
The Foreign Office, which has said family members of British diplomats are leaving Israel as a “precautionary measure”, has advised against all but essential travel to Israel and the Occupied Palestinian Territories.
The flights will be commercially operated and arrive in the UK, with vulnerable British nationals prioritised.
The Foreign Office said it will contact those eligible for the flights directly and British nationals should not make their way to the airport unless they are called.
Concerns remain high for the safety of British citizens in the region as the war, ignited by a bloody and wide-ranging Hamas attack on Israel at the weekend, has already claimed at least 2,400 lives.
At least 17 UK nationals are reported to be either dead or missing, including children, with Jake Marlowe, 26, the latest to be named among three known to have died in the incursion by Hamas fighters on Saturday.
Children and other dependents of British diplomats are expected to fly out of the country on the Government-arranged flights.
It is understood that British nationals, including dual nationals, and dependents travelling with a British national normally resident in the UK, will be invited to take up seats, and that tickets will cost £300.
The Israeli Embassy in the UK has said at least 100 people are believed to have travelled from the UK to Israel to serve in the Israeli military.
The embassy said it is understood those who travelled are “reservists and active duty soldiers” in the Israel Defence Forces.
On Thursday family members of some of those held hostage by Hamas in Gaza gave an emotional press conference in London.
Noam Sagi told reporters he should be celebrating his mother’s 75th birthday but she had been kidnapped by Hamas, branding the attacks a “second holocaust”.
He said: “These are peace-loving people who fought all their lives for good neighbouring relationships.
“If they will die for peace, they will take it. If they will die for war, that will be another travesty.”
The Duke and Duchess of Sussex have also spoken out about the violence, condemning “all acts of terrorism and brutality”.
Harry and Meghan stopped short of singling out sides in a statement on their Archewell Foundation website and vowed to support efforts to send urgent aid to the region.
The Sussexes’ statement came a day after the King and the Prince and Princess of Wales condemned the “barbaric acts” and appalling “horrors” inflicted in Hamas’s attack on Israel.
Meanwhile, Health Secretary Steve Barclay has insisted Israel has “the right to do everything it can” to rescue hostages in Gaza, amid reports the country is preparing to launch a ground offensive.
Asked on ITV’s Good Morning Britain whether he has fears over the level of Israel’s retaliation in Gaza and concerns there may be breaches of international law, Mr Barclay said: “We think international law obviously should be followed and civilian casualties should be minimised.
“But we should also be very clear that the reason for this situation is because Hamas has taken hostages into Gaza and the Israeli Government has the right to do everything it can to rescue those hostages.”
But the former head of MI6, Sir Alex Younger, urged Israel not to do “what your enemy wants” and said its intense retaliation could end up creating more terrorists.
International aid groups said deaths in Gaza could accelerate as Israel prevents the passage of food, water, fuel and medicine into the territory and after the region’s only power station ran out of fuel.
The International Committee of the Red Cross said hospitals in Gaza risk turning into morgues when their generators run out.
There have been calls for corridors to be established to allow aid in and civilians out.
Prime Minister Rishi Sunak spoke to Egyptian president Abdel Fattah el-Sisi on Thursday and offered the UK’s support to try to keep the Rafah border crossing between Egypt and Gaza open for humanitarian reasons, Downing Street said.
