"We will not tolerate these threats on our soil," UK Prime Minister Andy Burnham said. "We will crack down on Iran's use of criminal networks, using our full range of powers to target them."
British Prime Minister Andy Burnham said on Monday that a suspected plot targeting the RAF Fairford air base in Britain was "highly likely" to have been coordinated in Iran, and almost certainly directed by the Islamic Revolutionary Guard Corps.
The RAF Fairford base had been used by US bombers to carry out strikes on Iran, but last week, US President Donald Trump said a threat linked to Iran had prompted the removal of the planes.
US officials have told Reuters that there had been a suspected plot involving Iran to launch a drone attack.
"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)," Burnham told parliament.
The alleged plot came to light when five British men were arrested in the early hours of September 27 by three vans near the base on suspected terrorism and explosive offenses.
They were later released without charge on police bail "under stringent conditions". Police said petrol but no viable explosive had been found in the vans, and detectives said they were considering whether a foreign state had been involved.
Two other men, including a British-Iranian national, have also been arrested and released.
Burnham vows to crack down on Iranian state-sponsored violence
"We will not tolerate these threats on our soil," Burnham said. "We will crack down on Iran's use of criminal networks, using our full range of powers to target them and their funding streams, and we will bring further sanctions to restrict the capacity of Iran and the IRGC to do us harm."
Iran has rejected any suggestion it was involved in the incident at Fairford, saying it amounted to "unfounded and malicious speculations".
The British authorities have accused Iran of being involved in numerous plots in Britain.
In July, Britain used new powers designed to stop the use of state-sponsored proxies to ban support for the IRGC and a linked group accused of being behind attacks at locations linked to Jewish and Israeli communities, and Persian-language media.