The Guardian has released an image of the computer hard drives it was made to destroy by officials from Britain's security services.
Guardian journalist Glenn Greenwald has told ITV News the goal of anti-terror police who detained his partner David Miranda for nine hours at Heathrow was "to be thuggish and [to] intimidate".
In his first British TV interview, Mr Greenwald claimed he has been targeted by the security services since he started reporting on alleged state spying but said he doesn't fear for his safety.
Guardian journalist Glenn Greenwald has told ITV News not a "single comma" from his whistleblowing reports about state security has helped terrorism.
In his first British TV interview, he said "nothing has been revealed" about alleged state spying that "terrorists don't already know".
Guardian journalist Glenn Greenwald has told ITV News "even the most advanced intelligence services" would find it "impossible" to access information that he and his partner carry across the world because it is too well encrypted.
In his first British TV interview, Mr Greenwald refused to confirm what data his boyfriend David Miranda had confiscated by police when he was detained for nine hours at Heathrow Airport on Sunday as he headed back to Brazil.
The Guardian journalist whose partner was detained for nine hours under anti-terror laws at Heathrow Airport has given his first British TV interview to ITV News, revealing he is "angry" but "not surprised" by the police's action.
Glenn Greenwald told Brazil Correspondent Nick Ravenscroft he would not "allow emotion and anger" to "influence (his) journalistic and professional judgements".
He added: "I'm angry at what the UK did to my partner (David Miranda) but I'm not surprised."
You can see the interview in full on ITV News at Ten.
Guardian editor-in-chief Alan Rusbridger has told ITV News the detention of the partner of one of his journalists at Heathrow Airport was something out of an "Alice in Wonderland world".
He said holding David Miranda at the London airport for nine hours without a lawyer was a "misuse of a terror law to inhibit journalism".
Mr Rusbridger also said being ordered by a senior Whitehall official to destroy material that the newspaper already had copies of in Brazil and America was "one of the more bizarre days in Guardian history".
He claimed security officials were worried about Chinese and Russian agents "surrounding" the Guardian's London headquarters.
Home Secretary Theresa May confirmed she was briefed in advance of the detention at Heathrow Airport of David Miranda, the partner of a Guardian journalist who has written a series of stories on the US National Security Agency's mass surveillance.
Mrs May added that despite being informed of his detention, she does not make the decisions on who the police do and do not stop.
But she endorsed Mr Miranda's detention, saying: "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."
David Miranda's lawyers have written to Home Secretary Theresa May and Met Police Commissioner Bernard Hogan-Howe to express concern about his "unlawful" detention.
Criminal lawyer Kate Goold of Bindmans LLP said: "We are most concerned about the unlawful way in which these powers were used and the chilling effect this will have on freedom of expression."
A Conservative former minister has accused the Government of approving the detention of David Miranda, suggesting it had allowed police to "misuse" anti-terror laws.
David Davis said the Home Office, Foreign Secretary and "almost certainly the Prime Minister" would have been aware of the move to hold and question Miranda.
"No one's suggesting they directed it, but they approved it by implication," said Davis, who was Foreign Office Minister under John Major.
"If the Home Secretary is told this is going to happen and she does not intervene, then she's approving it," the MP added.