David Miranda is to mount a legal challenge over his detention at Heathrow Airport under terror legislation, Guardian editor Alan Rusbridger has said.
Mr Miranda, partner of Guardian journalist Glenn Greenwald, was detained at Heathrow Airport under Schedule 7 of the Terrorism Act 2000 as he changed flights on a journey from Berlin to his home in Brazil.
Greenwald is the reporter who interviewed American whistleblower Edward Snowden about the international surveillance activities of the US National Security Agency.
Meanwhile, a Downing Street source has said Number 10 was “kept abreast of the operation” to detain Mr Miranda, but denied any political involvement in the decision, adding: “The Government does not direct police investigations.”
British home secretary Theresa May has revealed she was briefed in advance of the possible detention of Mr Miranda at Heathrow.
But she said that it was not for her to tell the police who they should or should not stop at ports, or who they should arrest. She said: “If it is believed that somebody has in their possession highly sensitive stolen information which could help terrorists, which could lead to a loss of lives, then it is right that the police act and that is what the law enables them to do.”
However, a Conservative former minister has accused the British government of approving the detention, and suggested it had allowed police to use an anti-terror law in a way parliament had never intended.
David Davis, who was Foreign Office minister under former prime minister John Major, dismissed claims that the Home Office was not aware of the move to hold and question Mr Miranda.
Asked were there are questions the government needed to answer, he replied: “Of course there are.”
He added: “If the home secretary is told this is going to happen and she does not intervene, then she’s approving it.”
Mr Miranda had claimed he was held for nine hours by agents who questioned him about his “entire life” and took his “computer, video game, mobile phone, my memory card - everything”.
Mr Rusbridger told the BBC that Mr Miranda is to launch a civil action over his detention.
Schedule 7 applies only at airports, ports and border areas, allowing officers to stop, search, question and detain individuals.
Its use has been criticised by Greenwald as a “profound attack on press freedoms and the news-gathering process”, and has sparked widespread debate on the use of terror laws.
Rusbridger told the BBC Mr Miranda is launching a civil action over his detention. He said: “We will have to work out if that is legal or not, and that will be subject to legal challenge, I believe, by Glenn Greenwald and David Miranda, because it’s not clear that he was actually committing any offence in carrying material through Heathrow.
“I’m not aware of what that offence is.”
He went on: “I think there will be a legal challenge to the use of this very controversial bit, this Schedule 7, of the Terrorism Act and its use to obtain journalistic material.
“A lot of journalists the world over fly through Heathrow, and I think some of them now are going to be quite anxious about how the British authorities regard this bit of Britain that is not quite Britain but is Britain.”
Asked whether the Guardian would mount any challenge, he said: “At the moment this is a legal challenge by David Miranda, who is the individual, and he has lawyers who will mount that challenge.”
Rusbridger said: “He wants that material back and he doesn’t want it copied, and if the British state in whatever form - we’re not sure which bit of the British state we’re dealing with - wants to get that material, then they have to do it through more satisfactory procedure than this bizarre bit of the Terror Act that relates to ports and the transit lounges of airports.”
Rusbridger has also revealed that “shadowy” Government figures were sent in to destroy hard drives owned by the newspaper.
In a comment piece in the paper today, he said he held a series of meetings in which he was asked to destroy all Edward Snowden-related material.
He said he had received a call from a government official a month ago who told him: “You’ve had your fun. Now we want the stuff back.” The paper had been threatened with legal action if it did not comply.
Later, two "security experts" from the secretive Government Communications Headquarters (GCHQ) had visited the paper's London offices and watched as computer hard drives containing Snowden material were reduced to mangled bits of metal.
Rusbridger said the “bizarre” episode and the detention of Mr Miranda showed press freedom was under threat in Britain.
The Home Office has appeared to back Scotland Yard’s decision to detain Mr Miranda, saying the government and police “have a duty to protect the public and our national security”.
A spokesman said: “If the police believe that an individual is in possession of highly sensitive stolen information that would help terrorism, then they should act, and the law provides them with a framework to do that.
“Those who oppose this sort of action need to think about what they are condoning.
“This is an ongoing police inquiry so we will not comment on the specifics.”
Last night, Scotland Yard said the detention was subject to a "detailed decision-making process", saying: "Our assessment is that the use of the power in this case was legally and procedurally sound.
“Contrary to some reports, the man was offered legal representation while under examination and a solicitor attended. No complaint has been received by the Metropolitan Police Service at this time.”
David Anderson QC, the independent reviewer of terrorism legislation, has asked for an official briefing on the arrest, which he described as an “unusual case”.
The discussion raged on today after a petition launched by Four Lions actor Adeel Akhtar calling for the British government to urgently look at terrorism laws used to detain Mr Miranda was backed by more than 35,000 names less than 24 hours after it was started.
Shadow home secretary Yvette Cooper called on the home secretary to say whether she or the prime minister was informed about the decision, after a White House spokesman said it was given a "heads up" on the move to detain Mr Miranda.
Downing Street said the case was an “operational matter for the police”, but Ms Cooper said: “It isn’t good enough for the Home Office to dismiss this as a matter for the police.
“The White House have made clear it was ‘a decision by the British government’ and the police have said it was a ‘detailed decision-making process... reviewed throughout’.
“Given the sensitivity of this operation and the continued questions about the use of terrorism legislation in this case, Theresa May cannot simply refer this to the police.
“The home secretary needs to tell us whether she or the prime minister were informed or involved in this decision. Is it really possible that the American president was told what was happening but the British prime minister wasn’t?
“The government need to explain who authorised the use of terrorism legislation in this case and what the justification was.”