The foreign secretary has summoned the Iranian ambassador to make clear that “Britain will not tolerate threats on our soil” following last month’s incident at RAF Fairford.
Ed Miliband said attempts by Iran to undermine the UK’s security “through its criminal networks, proxy groups and state-backed malign activity is unacceptable”.
Prime Minister Andy Burnham told MPs the incident in Gloucestershire was “almost certainly directed by Iran’s Islamic Revolutionary Guard”, while the home secretary said the likely coordinator was a “known individual based in Iran”.
Iran’s ambassador to the UK, Seyed Ali Mousavi, said Tehran was not involved and was willing to cooperate with British authorities.
The Foreign Office has also sanctioned two Iranians, including the head of the regime’s counterespionage operations – with both men subjected to travel bans and asset freezes.
Burnham also indicated Iran could be hit with further sanctions over its suspected role.
It comes as the UK and 28 other countries – including the US, Canada, Australia, France and Germany – issued a joint statement condemning “in the strongest terms” violent attacks by Iran.
The statement accuses Tehran of carrying out “lethal plotting, arson, sabotage, cyber-attacks, and other hybrid activities” and also recognises the UK’s attribution of Iranian involvement in the incident at RAF Fairford.
A huge police operation began after officers were alerted to three suspicious vehicles near the base in the early hours of 27 September.
Dozens of homes were evacuated in the nearby village of Whelford and a large cordon was put in place around the site.
So far, a total of seven men – all in their 20s – have been arrested and later bailed in connection with the incident. No one has been charged.
Last week, Downing Street insisted the airbase was safe after the US withdrew all of its bombers – about a dozen B-1s from the base – back to their home stations on American soil.
In July, Iran said “any base used for aggression against Iranian territory constitutes a legitimate target for our forces”.
RAF Fairford, in the Cotswolds, has been used as a forward operating location by the US air force for decades.
In recent months, the US has flown B-1 and B-52 bombers from the base for the Middle East, after the UK approved an American request to use it for defensive strikes on Iran.
A US state department spokesman confirmed that US Secretary of State Marco Rubio had a call with Miliband on Monday where they discussed “holding Iran to account for its actions and of continued collaboration to secure US assets in the United Kingdom”.