The Mirror dismissed reports that the two journalists had attempted to put a fake bomb on a Channel tunnel train, and said that the “tracking device” is part of a series of investigations to test rail freight security.

“To be arrested under the Terrorism Act 2001 is more than alarming, it's completely disproportionate to the alleged crime,” the Daily Mirror head of news, Gary Jones, is quoted by Guardian Unlimited as saying. “Journalists should be fearing for the future of investigative journalism if journalists carrying out legitimate journalistic exercises are arrested under the Terrorism Act.”

Jones also said police had raided the homes of both men, taking a computer hard drive, notebooks and a video cassette from Parry's home.