Five men arrested over a suspected bomb plot at RAF Fairford have been released on bail as police investigate why they were so close to the US base in three vans with suspicious material in the back. This was reported by Qazaqyia.kz citing The Guardian.

The five suspects were revealed to be British men, all in their 20s and from London. They had been arrested in the Gloucestershire countryside early on Sunday morning on suspicion of explosives offences and preparing an act of terrorism, with an Iranian link a key line of inquiry.

Their release on police bail suggests that detectives believe it unlikely they were on the brink of a mass casualty attack by exploding a bomb close to the base, sources said.

An Iranian link is still under investigation, as is whether any of the five were paid to gather in the village of Whelford, 2 miles from RAF Fairford.

The prime minister, Andy Burnham, called a meeting of the government’s crisis committee Cobra over the events in the Gloucestershire countryside and Iran’s possible role.

An initial examination of the vans led police to suspect they carried explosive materials, with assessments made as to whether they were viable improvised explosive devices.

The head of UK counter-terrorism policing, assistant commissioner Laurence Taylor, said that the release of the men on bail did not mean the investigation was over and that they were subject to “stringent conditions”.

He added: “I know there is significant interest in whether the current geopolitical context has a bearing on this incident.

“At counter-terrorism policing we are working within this context every day, and at this stage we are keeping an open mind in this investigation. We have, as you would expect, ensured that our protective security advice and posture remain commensurate to the threat.

“But be assured, we are considering this from every possible angle.

“Including, that this may be activity committed by proxies, or individuals either knowingly or unknowingly, working on behalf of a foreign state.”

Iran is suspected of using proxies in the UK, from alleged arson attacks against Jewish targets to filming men flying a basic drone near the Israeli embassy.

Taylor said: “Often this threat becomes visible to us as criminal activity, often at a small scale and committed by individuals whose primary aim is not terrorism but a quick financial gain. It can be harder to spot, and to that end I would ask the public to remain vigilant and report anything suspicious to police.”

The US president, Donald Trump, on Sunday said the men “were looking to do big damage”, taken as revealing a serious terror plot.

Taylor said: “I can confirm that following extensive interviews and inquiries, the five men who were arrested are being released on police bail this afternoon.

“They absolutely remain under investigation as we explore multiple lines of enquiry.”

Police said the five men were all from London, one aged 23, three aged 24, and one aged 25, and were British nationals.

They were arrested after a farmer driving home from a party spotted them, and said she believed they were wearing balaclavas and ran away when her headlights illuminated them. She then called the police.

Trump had also suggested the plot was known to the US authorities. But British sources suggesting the specific activities of the men was unknown.

The base had been at its highest state of alert, called delta, for several days beforehand because of a general threat with extra security measures.

The farmer said she was surprised it was left to her to disrupt the activities of the men.

In a round of broadcast interviews, the defence secretary, Wes Streeting, said he only had a “partial picture” of the events in a round of broadcast interviews.

At the Labour party conference, the home secretary, Shabana Mahmood, said evacuated residents should shortly be able to return home. About 85 households in the Cotswolds village of Whelford were evacuated early on Sunday morning to a leisure centre, with a 400-metre cordon placed around the white vans as bomb disposal robots examined them.

Iran’s Islamic Revolutionary Guard Corps had made threats against RAF Fairford in July.

Iran’s embassy in London denied any involvement in the events in Whelford: “The embassy of the Islamic Republic of Iran in London categorically rejects and strongly condemns the recent unfounded and malicious speculations published by some British individuals and media outlets attempting to link Iran to arrest of five suspects in the vicinity of RAF Fairford base.

“The circulation of such fabricated speculations, particularly in the aftermath of the criminal acts of aggression committed by the United States and the Israeli regime against the Iranian people, will serve no purpose other than to fuel Iranophobia propaganda in the UK.”