Rishi Sunak’s government has unveiled new sanctions against seven individuals linked to Iran, for allegations including assassinations and threats to life in Britain and other countries.

       The move came hours after the UK blamed Iran-backed militia for the drone strike on an American base in Jordan which saw three US troops killed. Tehran has continued to deny any involvement.

       Joe Biden vowed the US would “respond” after also blaming Iran-backed groups, while Republican president favourite Donald Trump said the Democrat had put the country “on the brink of World War 3”.

       Announcing new sanctions, foreign secretary David Cameron said the Iranian regime and “the criminal gangs who operate on its behalf” pose an unacceptable threat to UK security.

       Asset freezes were announced against five Iranians and two Turks, as well as against a unit of the Islamic Revolutionary Guard Corps Quds unit said to have targeted people in Britain.

       Lord Cameron said: “Today’s package exposes the roles of the Iranian officials and gangs involved in activity aimed to undermine, silence and disrupt the democratic freedoms we value in the UK.”

       “The UK and US have sent a clear message – we will not tolerate this threat,” he added.

       The Foreign Office said the sanctions were being imposed after an ITV investigation into plots to assassinate two television presenters from the Iran International TV channel in the UK. At least 15 such threats are said to have been made since January 2022.

       An Iranian that the Foreign Office said was the head of an international drug and trafficking cartel was also targeted for allegedly planning or conducting overseas attacks.

       The sanctions package co-ordinated with the US comes amid heightening tensions in the Middle East since the Israel-Hamas war started on 7 October.

       Both No 10 and the White House have blamed Iran-linked militias for the strike on Tower 22 base, near the Syrian border, which killed three US service personnel. At least 34 US troops were also said to have been injured.

       “We are concerned and would urge Iran to continue to de-escalate tensions in the region,” Mr Sunak told broadcasters on a trip to the north-east on Monday. “We absolutely condemn what has happened over the past couple of days.”

       The Islamic Resistance in Iraq has claimed it is responsible for the strike. US officials were working to identify the group behind the attack but have so far assessed that one of several Iranian-aligned groups was responsible.

       Iran has denied any involvement. Nasser Kanaani, spokesman for Iran’s foreign ministry, said it was “not involved in the decision making of resistance groups” in the way they choose to “defend Palestinians”.

       Labour leader Sir Keir Starmer has said those behind the deadly drone strike on a US base in Jordan should be “held to account” – but said everything must be done to prevent escalation.

       “I am concerned about the possibility of escalation of an already dangerous situation in the Middle East,” he told broadcasters.

       “So we have to see this in that context and do everything that we can to ensure there isn’t escalation of the conflict, and on the contrary, that we find ways to bring this conflict to the immediate end.”

       Asked whether MPs should get to vote on further UK military action, Sir Keir said: “I think it’s important that we judge each intervention on its merits.”

       Since Hamas launched its attack on Israel on 7 October, Iranian-backed militias have struck US military sites in Iraq more than 60 times. In Syria, they have struck more than 90 times with drones, rockets, mortars and ballistic missiles.

       Militias have said that their strikes are in retaliation for Washington’s support for Israel in the war in Gaza, and aim to push US forces out of the region.

       The US in recent months has hit targets in Iraq, Syria and Yemen in response to attacks on its forces and to diminish the threats from Iranian-backed Houthi rebels to commercial shipping in the Red Sea. Britain has joined two strikes against the militants, though they so far seem to have done little to deter Houthi action.

       Meanwhile, No 10 also defended the pause in funding for UNRWA over allegations staff from the agency helped Hamas with its 7 October attack on Israel. Downing Street said no further funding had been expected to be released to the agency in the coming weeks.

       Mr Sunak’s spokesperson said: “My understanding is that we have committed ￡16 million to UNRWA following the Hamas terror attacks, but this was dispersed before the allegations came to light.”

       Labour’s Jonathan Ashworth said the allegations “absolutely appalling” – but argued the UN agency’s programmes should be allowed to continue.

       The shadow cabinet minister told Sky News: “What is happening is a catastrophe which is why, for example, we’ve also called for a halt in the fighting, an immediate humanitarian truce, a ceasefire, a sustained ceasefire is needed, but UNRWA programs have to continue.”