Donald Trump is facing cross-party calls on Capitol Hill to ditch his controversial diesel deal with Russia, which has sparked criticism in the UK.

A group of six Republican and six Democrat senators has jointly warned that the lifting of sanctions to allow Moscow to sell the fuel is “a gift to our adversary and a betrayal of our allies”.

The US president has defended the decision as he seeks to increase supply and so bring down soaring pump prices ahead of critical stateside elections next month, which will decide control of Congress.

But critics argue it will bolster the Kremlin’s coffers and help bankroll Russian President Vladimir Putin’s war against Ukraine.

The deal has led to renewed tensions between Washington, Kyiv and its allies, including the UK.

Fuel prices have spiked as a result of the US war with Iran, which has disrupted oil supplies through the Strait of Hormuz waterway, but Mr Trump has increasingly sought to lay the blame on attacks by Ukraine on Russian refineries.

In the face of diplomatic strains, Britain has rallied to the support Ukraine’s Volodymyr Zelensky, after the US president suggested he should be replaced as the country’s leader and claimed Mr Putin, who triggered the conflict by launching the invasion back in 2022, wanted a peace deal more.

In their letter to Mr Trump, the senators argue the agreement to waive sanctions on Russia’s diesel exports “only provides Putin with more fuel to finance his war machine and enables Russia to continue its brutal attacks on Ukrainian civilians”.

It added: “Granting Moscow the ability to sell Russian diesel freely in global markets damages American security interests and is a betrayal of the people of Ukraine, who continue to defend themselves from Putin’s murderous, illegal war.

“This deal is a gift to our adversary and a betrayal of our allies; it should be rescinded.”

They also argue it “will offer limited to no relief to Americans”.

The senators instead urged the president to impose sweeping new sanctions, under legislation introduced last month, aimed at putting the financial squeeze on the Moscow war machine.

The provisions of the law, championed by the late Republican senator Lindsey Graham and backed by the UK Government, included the power to impose tariffs of up to 100% on major buyers of Russian oil and gas, such as China and India.

The senators said the economic pressure would enhance the president’s negotiating position “to bring a swift end to this ruinous conflict”.

They added: “For decades, America has stood as the bastion of freedom against tyranny, and American presidents have embodied our nation’s resistance to tyrants. Putin is a tyrant.”

Earlier, Mr Trump insisted the deal with Russia to supply diesel was for “the world”.

He said: “That’s not being released to us. That’s a diesel deal that’s going to be released into the world for the world market because the world market suffered with high prices, and when you knock out diesel refineries, that’s not a great thing.”

He added: “It’s not a deal with me. It’s a deal for the world.”

Meanwhile, Tory leader Kemi Badenoch said Mr Trump was “wrong” to attack Mr Zelensky and described his decision to “go backwards” on Russian oil sanctions as “disappointing”.