British Prime Minister Sir Keir Starmer says his country will recognise a Palestinian state as early as September, unless Israel takes significant steps to end the war in Gaza.
Sir Keir made the announcement in London on Tuesday, local time.
It came less than a week after French President Emmanuel Macron pledged that his country would recognise Palestine as a state at a United Nations meeting in September.
France will be the first G7 nation to do so.
Sir Keir's announcement came one day after he met Donald Trump in Scotland, but the US president said they "never discussed this".
"Our overwhelming concern is for the Israeli hostages and for the people of Gaza. We must do all we can to end the current suffering and change the situation on the ground," a statement released by Downing Street read.
"We demand an immediate ceasefire to stop the slaughter, that the UN be allowed to send humanitarian assistance into Gaza on a continuing basis to prevent starvation, and the immediate release of the hostages. We support the US, Qatari and Egyptian governments in their attempts to bring about a ceasefire."
According to a Downing Street statement, Britain will recognise Palestine as a state unless the Israeli government "takes substantive steps to end the appalling situation in Gaza, reaches a ceasefire, makes clear there will be no annexation in the West Bank, and commits to a long-term peace process that delivers a two-state solution".
Sir Keir took the decision after recalling his cabinet during the summer holidays on Tuesday to discuss a new proposed peace plan being worked on with other European leaders and how to deliver more humanitarian aid to Gaza.
Trump says he 'never discussed' UK plan
Israel's foreign ministry responded to the UK's move by labelling it a "reward for Hamas" and it accused the UK of harming efforts to reach a ceasefire.
Speaking to reporters on Air Force One on Tuesday, US President Donald Trump expressed similar sentiment, saying: "You could make the case that you're rewarding people, you're rewarding Hamas."
Mr Trump was on his way back to the US from his Scottish golf course, a day after meeting Mr Starmer.
"We never discussed this, surprisingly … maybe a little bit at the news conference, but he was sort of discussing it with you," he said.
Mr Trump said he "had no view" on Sir Keir's announcement, adding that his focus was on getting aid and food into Gaza.
"We want to take it one thing at a time. They need food and they need people to be able to get them the food."
UK calls for end to 'appalling situation'
While Australia has also reiterated its commitment to a two-state solution over the course of the war in Gaza, Sir Keir's language on Tuesday, and provision for a concrete timeline, is stronger than anything his counterpart in Canberra, Anthony Albanese, has used.
Moments after Sir Keir's announcement, British Foreign Secretary David Lammy made a speech at the UN in New York in which he said the UK "intends" to recognise a Palestinian state in September.
"We will do it unless the Israeli government acts to end the appalling situation in Gaza, ends its military campaign and commits to a long-term sustainable peace based on a two-state solution," he said.
Mr Lammy said the UK's support for Israel was "steadfast" but warned the Netanyahu government's rejection of a two-state solution was "wrong morally".
"It harms the interests of the Israeli people, closing off the only path to a just and lasting peace."
Global pressure on Israel amid famine concerns
The UN had today began a three-day conference, being hosted by France and Saudi Arabia, to talk about a two-state solution.
Tuesday's announcement comes as figures released by Gaza's Hamas-run health ministry said the death toll in the territory during the war had passed 60,000.
International pressure has been building on Israel to take action in recent weeks, with a United Nations-backed organisation on Tuesday warning that famine was "playing out" in Gaza.
The Integrated Food Security Phase Classification warned that there was "mounting evidence [showing] that widespread starvation, malnutrition, and disease are driving a rise in hunger-related deaths", adding that this was the "worst-case scenario" for famine.
Israel has relaxed restrictions on allowing aid into the Palestinian territory in recent weeks, including this weekend, but aid organisations warn it is not enough.
Senior members of the Israeli government, including Israeli Prime Minister Benjamin Netanyahu, have repeatedly rejected claims of widespread starvation in Gaza.
While there had been hopes of a ceasefire being reached between Israel and Hamas, the militant group which governs Gaza and is designated a terrorist organisation by the Australian government, meetings in Italy in Doha last week amounted to nothing.
