Prime Minister Andy Burnham told the House of Commons on Monday that a suspected plot against RAF Fairford in Gloucestershire was highly likely to have been coordinated in Iran and almost certainly directed by the Islamic Revolutionary Guard Corps.
Mr Burnham said: "I can confirm our assessment that it is highly likely to have been coordinated in Iran, almost certainly directed by Iran's Islamic Revolutionary Guard (IRGC)."
According to Reuters, five British men were arrested near the base in the early hours of 27 September on suspected terrorism and explosives offences.
The five were later released without charge on police bail "under stringent conditions", Reuters reported. Two other men, including a British-Iranian national, were also arrested and released.
UPI reported that seven men had been arrested and released in total, and that no one had been charged. Reuters described the details made public so far as "thin".
Detectives said petrol, but no viable explosive, was found in vans seized with the five men, according to Reuters.
US officials told Reuters there had been a suspected plot involving Iran to launch a drone attack. The UK government has not confirmed this, and the officials were not named.
Reuters also reported that President Donald Trump said last week that an Iran-linked threat had prompted the decision to withdraw bombers from the base. Israel's Ynet news site reported that 12 B-1 bombers were withdrawn. That figure has not been confirmed elsewhere.
Mr Burnham also said there would be more sanctions on Iran, according to UPI. It reported that two individuals had been sanctioned over espionage and attacks on behalf of Iran in Europe and the US.
Foreign Secretary Ed Miliband said he had summoned the Iranian ambassador, France 24 reported. No account of the meeting had been published.
Ynet quoted Mr Burnham as telling MPs: "We will not tolerate these threats on our soil."
Iran's Ambassador to Britain, Seyed Ali Mousavi, rejected the claims, according to Iranian state news agency IRNA, as quoted by Reuters and France 24.
Mr Mousavi said Tehran had had no involvement in the matter. He said that if the British government had documents or evidence to support its claims, it should present them.
Arab News reported that Iran described the allegations as "unfounded and malicious speculations". It was not clear who made that statement. No direct response from Iran's Foreign Ministry or the IRGC had been reported.
The UK's attribution is described as an assessment. No public evidence had been presented, and no one had been charged.
Mr Burnham had said on 1 October that there were "strong indications" of an Iranian link, according to the Washington Post.
RAF Fairford is a Royal Air Force station in Gloucestershire that hosts US Air Force aircraft. It was among the British bases Mr Trump asked to use as a staging ground for strikes on Iran.
The US and Israel have been at war with Iran in 2026. The Washington Post describes the war as ongoing and says US bombers from Fairford have been used to strike Iran.
Mr Mousavi earlier told Times Radio that Tehran was "considering" whether British bases were legitimate targets. He called the use of Fairford by US B-1 and B-2 jets "very unfortunate", according to The Independent.
The IRGC is Iran's ideologically driven military force, separate from the regular army. Its Unit 840 is reported to carry out covert operations abroad.
In May 2025, UK counter-terrorism officials arrested five Iranian citizens over a suspected plan to attack the Israeli embassy in London. Evidence suggested Unit 840 was behind it, and Iran denied involvement.
That case increased pressure in the UK to label the IRGC a terrorist group.
The investigation into the Fairford incident continues, with the men on bail. No date had been given for any decision on charges, and the government has promised further sanctions on Iran.
