PRIME Minister Andy Burnham has said there are “strong indications” Iran played a part in the alleged RAF Fairford terror plot as the mystery continues to grow.

His comments come as cops continue to investigate the bizarre series of events outside the Gloucestershire airbase, where five men were arrested in the early hours of Sunday.

The suspects, all British nationals in their 20s and from London, have since been released on bail.

Burnham told GB News: “So what I can say is there are strong indications that Iran played a part in what happened over the weekend.

“It is, though, still an ongoing and very serious police investigation.

“So I hope you’ll understand that I don’t say more at this point, but I wanted to confirm what we could say.”

He added: “It’s obviously a very serious investigation involving our colleagues in the United States, and we are working very closely with them.

“And I will say more when I can.”

The development comes after counter-terror cops searched three white vans found blocking a road near RAF Fairford.

No improvised explosive devices were found, although a quantity of petrol was recovered.

The Sun understands large plastic barrels of fuel were found inside the vehicles and were initially thought to contain chemical explosives.

Cops are now examining a number of possible explanations for why the men were there, including whether they were acting as Iranian proxies.

Other lines of inquiry include whether they were carrying out surveillance, testing the base’s security in a “dry run” or attempting to send a message to the British Government.

The case took another bizarre turn after The Times reported that one of the suspects had called 999 himself before the arrests.

It is not known why the man made the call and only deepens the mystery engulfing the case as question marks are raised over the suspect’s motives for calling the police on themselves.

The reported call could explain why cops were responding at around 12.45am, before a local farmer raised the alarm at around 1.36am.

The farmer had spotted three vans blocking the road near Whelford as she drove home with her husband.

She told The Sun: “We had to turn around and drive away.

“When we did that, we saw a group of men with masks and balaclavas running in front of us.”

She tried to contact the airbase but was unable to get through before calling 999.

Around 85 homes in nearby Whelford were evacuated as armed cops descended on the scene.

Exclusive footage shared with The Sun showed one of the white vans travelling towards RAF Fairford at around 11.15pm on Saturday.

The vehicle was captured on a resident’s doorbell camera less than a mile from the airbase, just hours before the arrests.

RAF Fairford is used by the US military and has been involved in operations against Iran.

US President Donald Trump has repeatedly criticised the decision to release the five suspects on bail.

He previously said he was “surprised” by their release and that he would not have granted them bail.

US Secretary of State Marco Rubio has also previously said a “foreign actor” was involved, while pointing towards Iran.

Counter Terrorism Policing has stressed that the investigation remains ongoing and that officers are keeping an open mind.

Assistant Commissioner Laurence Taylor said searches of the vans had concluded and confirmed that no viable explosive devices had been found.

Speculation grew that the men could have been fuel thieves, after the head of the UK’s National Counter Terrorism Policing, Assistant Commissioner Laurence Taylor, said a “quantity of petrol” was found.

In a statement yesterday he said: “As part of the investigation, we have searched properties in London which I can confirm have concluded.

“We can confirm that no improvised explosive devices were found [in the vans]. However, a quantity of petrol was recovered.”