'It's too late now!' Donald Trump slams Keir Starmer in front of G7 leaders in tense Iran row, officials claim

Despite Sir Keir later reversing his decision to enable the US to carry out "defensive" strikes on Iranian missile sites, Axios reported Mr Trump said: "You should have proposed it before the war — now it is too late."

However, there is no indication of the tense exchange from No10's readout of the call on March 11.

A Downing Street spokesman said: "The Prime Minister spoke to G7 leaders this afternoon to discuss the latest situation in the Middle East and action to manage the economic impacts of the conflict and support regional partners.

"He reaffirmed the long-standing position that Iran must abandon its nuclear ambitions and set out how the UK had authorised the US to use British bases for defensive operations to target Iranian missiles at source."

The remarks are said to have occurred during showdown G7 talks about the ongoing war in the Middle East and its growing global impact.

German Chancellor Friedrich Merz and French President Emmanuel Macron are said to have joined Sir Keir in urging Mr Trump not to allow Russia to benefit from the conflict.

The US Treasury has announced a one-month waiver on sanctions related to Russian oil shipments already in transit.

Treasury Secretary Scott Bessent said the move was aimed at stabilising global energy markets, currently unsettled by the Middle Eastern conflict which has made moving through the Strait of Hormuz virtually impossible.

The vital shipping lane’s closure has pushed oil prices above USD 100 per barrel, prompting the US to explore other means.

Officials claim the waiver would not significantly benefit the Russian government as it only applies to oil shipments with no connections to Iran.

Mr Trump and Sir Keir have been at odds since the crisis erupted in Iran.

The Prime Minister said last week the UK would not join the US and Israel in their attacks on Iran, but agreed to let the US use British bases for defensive strikes on Iranian missile sites.

Mr Trump said he was “not happy with the UK”, adding that Sir Keir was “no Winston Churchill”.

The pair spoke in a phone call last week, and Downing Street said in a statement: "The leaders began by discussing the latest situation in the Middle East and the military cooperation between the UK and US through the use of RAF bases in support of the collective self-defence of partners in the region.

"The prime minister also shared his heartfelt condolences with President Trump and the American people following the deaths of six US soldiers.

"They looked forward to speaking again soon."