The 25-year-old was the sixth man detained as counter-terrorism police investigate ‘possible foreign state involvement’

A sixth man who was arrested in connection with a suspected terrorist plot at RAF Fairford has been released on bail.

The 25-year-old, a dual UK-Iranian national, was arrested on suspicion of preparing terrorist acts under section 5 of the Terrorism Act 2006.

He was detained on Thursday in the borough of Westminster, London, where searches of two properties have now concluded.

The investigation into the incident is still under way, counter-terrorism police said.

Last weekend, five British nationals, all in their mid-20s, were arrested on suspicion of explosives offences and terrorism and then bailed.

The arrests were made after three suspicious vans were spotted near the military site in Gloucestershire.

Screengrab of men being detained.

Vicki Evans, the senior national coordinator for Counter Terrorism Policing, previously said the investigation was “hugely complex”, adding that specialist teams were “interrogating multiple lines of inquiry”.

She said: “As we’ve made clear, we’re looking at all possible angles – including possible foreign state involvement.”

The prime minister, Andy Burnham, has said there were “strong indications” Iran played a part in the incident near the Gloucestershire military base.

RAF Fairford has been used in recent months by US bombers after former prime minister Keir Starmer granted Washington permission to use British bases for “defensive” strikes against Tehran.

Bomber taking off.

Counter-terrorism police have said a quantity of petrol, but no explosive devices, was found in the vans that had sparked the security alert near the airbase.

On Thursday, the Israeli prime minister, Benjamin Netanyahu, claimed Israel handed Britain intelligence about the suspected terror plot.

Netanyahu said his country warned UK authorities about the “Iranian-sponsored attack” shortly before Britain’s announcement of a ban on trade with illegal Israeli settlements in the West Bank.