Jeremy Corbyn has called for the Government to abstain from escalating tensions with Iran without “credible evidence” that Tehran was responsible for attacks on two oil tankers.

The Labour leader warned Britain risked increasing the threat of war after the Foreign Office (FCO) said it was “almost certain” in its assessment that “a branch of the Iranian military… attacked the two tankers on 13 June”.

“No other state or non-state actor could plausibly have been responsible,” the FCO said, pointing to a “recent precedent for attacks by Iran against oil tankers”.

Foreign Secretary Jeremy Hunt condemned the attacks, saying they built on “a pattern of destabilising Iranian behaviour and pose a serious danger to the region”.

On Friday, the US released footage said to show an unexploded mine being removed from one of the tankers by Iranian special forces.

But Iranian president Hassan Rouhani accused the US of “carrying out an aggressive policy and posing a serious threat to regional stability”.

Tehran’s foreign minister, Javad Zarif, earlier said the US “immediately jumped to make allegations against Iran without a shred of factual or circumstantial evidence”.

Mr Corbyn tweeted: “Britain should act to ease tensions in the Gulf, not fuel a military escalation that began with US withdrawal from the Iran nuclear agreement.

“Without credible evidence about the tanker attacks, the government’s rhetoric will only increase the threat of war.”

Mr Hunt said Britain’s assessment “leads us to conclude that responsibility for the attacks almost certainly lies with Iran”.

“These latest attacks build on a pattern of destabilising Iranian behaviour and pose a serious danger to the region,” he said.

“We call on Iran urgently to cease all forms of destabilising activity. The UK remains in close coordination with international partners to find diplomatic solutions to de-escalate tensions.”

On Friday, US president Donald Trump told Fox News that Iran “did do it”.

“I guess one of the mines didn’t explode and it’s probably got essentially Iran written all over it. And you saw the boat at night trying to take the mine off and successfully took the mine off the boat, and that was exposed,” he said.

The price of oil rocketed on Thursday amid fears of disruption to one of the world’s most important tanker routes as a result of instability in the region.

The suspected attacks came after four commercial ships were “subjected to sabotage operations” in the Arabian Gulf in May.

The FCO said a UAE-led investigation concluded that they were conducted by “a sophisticated state actor”.

“We are confident that Iran bears responsibility for that attack,” the FCO said.