US President Donald Trump on Thursday said he disagreed with British Prime Minister Keir Starmer over a UK plan to recognise a Palestinian state.

"I have a disagreement with the prime minister on that score -- one of our few disagreements," Trump said at a press conference with Starmer after bilateral talks.

"I want an end. I want the hostages released," said Trump, calling the war "complex" but avoiding directly answering multiple questions about whether he would urge his ally Prime Minister Benjamin Netanyahu to end Israeli bombing in Gaza.

Starmer called the situation in Gaza "intolerable" and stressed the "need to get aid into Gaza at speed".

The US president also said that Vladimir Putin has "really let me down" over the war in Ukraine, as Keir Starmer called for more pressure on the Russian leader.

Trump said failing to end the conflict was his "biggest disappointment" but did not set out his next steps against Putin.

Trump has urged Western allies to stop buying Russian oil to force Putin to the negotiating table, but has held back from taking any further unilateral actions against Moscow.

Meanwhile, Keir Starmer said London needed to "ramp up" the removal of irregular migrants from Britain to France, after the first deportation under a new deal took place earlier Thursday.

"We need to ramp that up at scale, which was always envisaged under the scheme but it's very important that we have been able to prove the proof of concept," Starmer told reporters at the press conference alongside Donald Trump, who urged the British leader to "stop" migration.

The British PM called Thursday for extra pressure on Vladimir Putin to end the war in Ukraine, after visiting US President Donald Trump said the Russian leader had let him down.

"We have to put extra pressure on Putin, and it's only when the president has put pressure on Putin that he's actually shown any inclination to move. So we have to ramp that pressure up," Starmer said.