Five British men detained near a US airbase in England have been released on bail but remain under investigation, the head of UK counter-terrorism policing has said. The men, all in their twenties and from London, were detained early on Sunday after three vans were spotted near RAF Fairford in Gloucestershire. They were bailed on Monday. Laurence Taylor, head of UK Counter Terrorism Policing, said the men remain under investigation under stringent conditions. He said lines of inquiry include the possibility that they were acting as proxies for a foreign state, with Iran, Russia and non-state groups all named as possibilities. The Press Association reported that no viable explosives were found. Iran's embassy in London denied any involvement. Around 85 homes in the village of Whelford were evacuated as a precaution. US Secretary of State Marco Rubio said the incident clearly involves the hands of a foreign actor, according to Fox News. The investigation continues amid heightened tensions over suspected Iranian-linked plots on Western soil.