Sir Keir Starmer has been accused of of “letting down” Ukraine after the UK quietly relaxed sanctions on Russian crude oil in a move which critics fear will be a major boost to Vladimir Putin.

The move was condemned by senior Labour MP Dame Emily Thornberry, chair of the Foreign Affairs Select Committee, and branded “insane” by Tory leader Kemi Badenoch – coming at a time when Sir Keir’s energy secretary Ed Miliband is blocking the UK from drilling for its own oil and gas reserves.

The government previously said it would block Russian oil refined in third countries in a bid to “further restrict the flow of funds to the Kremlin”.

But, with prices surging as a result of the Iran war, Sir Keir has shifted his stance and will now allow for the import of jet fuel and diesel refined in third countries.

Ministers have sought to defend the measures as “protecting the UK national interest” with the closure of the Strait of Hormuz and the ongoing crisis in the Middle East causing costs to soar.

But Dame Emily hit out at the government’s decision and said the people of Ukraine have been “very let down” by the move.

“We are talking about our allies in Ukraine who have been fighting a war bravely against Russia for years and years with our support,” the Labour MP told BBC Radio 4’s Today programme.

“They have looked to Britain as one of their most important allies, and they don’t understand, given that we promised that we would stop this loophole in October, and we still haven’t done it. In fact, it seems to have got worse. People feel very let down.”

Ukrainian MP Oleksiy Goncharenko said the decision puts a “question mark” over the UK’s friendship with Ukraine, as he warned it shows Russian that “everything can be bought and everything is at sale”.

“I’m deeply disappointed,” he told Times Radio. “One of the things which we felt in Ukraine very strongly was that United Kingdom was always supporting Ukraine on the very high level, and we were appreciating it very much. And that was important part of our also resilience, knowing that there are real true friends in countries like UK, which supported us really seriously.

“And now that this decision puts it on the question mark because I really can’t understand it. I think it’s a wrong decision. I think that shows to Russia that in the end of the day, everything can be bought and everything is at sale.”

Tory leader Kemi Badenoch described the move to waive some of the sanctions as “insane”.

She posted on X: “After 18 months of ‘standing up to Putin’ the Labour govt quietly issued a licence allowing imports of Russian oil refined in third countries.

“Yesterday Labour MPs voted against UK oil and gas licences. We are now importing from Russia instead of drilling in the North Sea. Insane.”

John Foreman, associate fellow of the Russia and Eurasia programme at Chatham House, called the decision “appalling”, and warned it will “do little for UK consumers” while letting down Ukraine.

“Starmer has posed self righteously as the leader of the coalition of the willing for two years but under pressure he has caved,” he told The Independent .

“A combination of moral vacuity and energy policy incompetence. Ukraine sacrificed on Ed Miliband’s high altar of Net Zero.”

Lib Dem leader Sir Ed Davey said there was a “trade off” to be made over cost-of-living pressures and support for Ukraine.

He told Sky News: “The government has a real challenge here, because this appalling war in Iran is pushing up the cost of living, is pushing up diesel and petrol prices.

“But we’ve also got to remember that we need to support our Ukrainian allies. They are fighting and paying a heavy, heavy price to beat that appalling Russian invasion, they’re on the front line of our defence and security, and the question is, has the government got that trade off right?”

He said his party would look at the detail of the proposal, adding: “We’re really, really worried if there’s any undermining of our support for Ukraine.”

US treasury secretary Scott Bessent, earlier this week, extended a 30-day sanctions waiver allowing the purchase of Russian oil shipments already at sea.

Sir Keir risked opening a fresh rift with Donald Trump earlier this year by vowing that Britain wouldn’t be following the US in lifting sanctions on Russian oil, saying that the move risks helping Putin’s “war machine”.

Just two months later however, ministers are being forced to defend the decision to ease restrictions on Russian oil.

Treasury minister Dan Tomlinson told Sky News: “When there are international conflicts, we’ve just been talking about the conflict in Iran, talking about the conflict in Russia … what we have to do as a government is make sure that we’re protecting the UK national interest, making sure that this impact of conflicts that wash up on our shore, that we’re protecting individual families.”

He later added: “The government has announced yesterday this time-limited change to the rules around oil and refining given the extremes of the impacts of the conflict in Iran, and the impact of it washing up on our shores.”