British citizens leaving Gaza will be exempt from residency tests.
Prime minister Rishi Sunak said UK Border Force teams are set up in Egypt to “quickly” assist British nationals in leaving the region.
People fleeing the war and in the wider region of Lebanon and the West Bank will also be able to claim universal credit, as well as disability and child benefits, “without delay”.
They will also be able to access social housing and housing assistance if needed.
The government said it would also ensure that money paid under the victims of overseas terrorism compensation scheme would not be counted when working out entitlement to income-related benefits.
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The announcement comes as the UK ramps up its humanitarian aid to Gaza, with Rishi Sunak announcing earlier this week that the government would provide a further £20m in funds – on top of an existing £10m – taking the total package this year to £57m.
Work and Pensions Secretary Mel Stride said: “We’ve been working quickly to ensure British nationals arriving from Israel, the Occupied Palestinian Territories and Lebanon can receive the support and security they need during a time of unspeakable turmoil.
“As the UK continues to step up its response to the fast-moving circumstances in the region, the regulations which come into force today will speed up access to benefits, ensuring those eligible can access the help they need.”
The government said that where arrivals do not have immediate accommodation available, local authorities may provide emergency overnight accommodation before supporting people into more secure accommodation.
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Those who meet the exemption will be supported more quickly but it will not impact who local housing authorities should prioritise for social housing, the government said.
At least 12 British nationals were killed in the attack by Hamas on 7 October, which saw 1,400 Israelis killed.
A further five UK nationals are missing, Downing Street said this week.
Mr Sunak has been joined by the Labour Party in calling for a humanitarian pause to allow aid to reach Palestinians and to create a “safer environment” for UK citizens to leave Gaza.
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In recent days Israel has allowed aid into the country through the Rafah crossing between Egypt and Gaza after it previously limited essentials such as water, food and fuel to the area, which is home to 2.2 million civilians.
Speaking at an event in central London about artificial intelligence on Thursday, Mr Sunak said the government recognised that there needed to be a “safer environment, which of course necessitates specific pauses, which are distinct from a ceasefire”.
“We’re very keen to be able to bring them out and bring them home,” he said.
“What I can tell you is we’ve pre-positioned Border Force teams to Egypt.
“So that if our nationals can cross the Rafah crossing, we’re ready to get them in and bring them back.
“It is not something we can do immediately but when the moment arises, we’ll be ready to take it quickly.”
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On the same day, Deputy Prime Minister Oliver Dowden chaired a COBRA meeting in which he discussed the situation in the Middle East and the next steps in pushing for the release of hostages held by Hamas.
More than 200 from many different countries remain captive inside Gaza.
Mr Dowden said he was “heartbroken” at the mounting casualties in Gaza – where the Hamas-run Gaza health ministry claims 7,000 people have been killed by airstrikes – but that Israel could not “eliminate” Hamas “without there being some civilian impact”.
“The way to stop further losses of innocent civilian lives is to remove the terrorist threat and to move to a position where we can restore stability and peace to this region,” he told Sky News.