The British authorities forced the Guardian newspaper to destroy material leaked by Edward Snowden, its editor has revealed, calling it a “pointless” move that would not prevent further reporting on US and British surveillance programmes.

In a column yesterday, Alan Rusbridger 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 at London’s Heathrow airport on Sunday of the partner of Guardian journalist Glenn Greenwald showed press freedom was under threat in Britain.

The nine-hour detention under an anti-terrorism law of David Miranda, Greenwald’s Brazilian partner, has caused a furore with Brazil, British opposition politicians, human rights lawyers and press freedom watchdogs among those denouncing it.

Greenwald was the first journalist to publish US and British intelligence secrets leaked by Snowden, the former US National Security Agency (NSA) contractor who is wanted in the US and has found temporary asylum in Russia.

Under mounting pressure to explain itself, the Home Office defended Miranda’s detention. “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,” it said in a statement.

The Metropolitan Police said Miranda’s detention had been “legally and procedurally sound”.

Miranda, who was in transit on his way from Berlin to Rio de Janeiro where he lives with Greenwald, was questioned for nine hours before being released without charge minus his laptop, mobile phone and memory sticks.

He had been ferrying materials obtained from Snowden between Greenwald and Laura Poitras, an independent film-maker based in Berlin who has also published reports based on Snowden material.

“This law shouldn’t be given to police officers. They use it to get access to documents or people that they cannot get the legal way through courts or judges. It’s a total abuse of power,” Miranda told the Guardian after returning home.

The White House yesterday said Washington was given a “heads up” ahead of Miranda’s detention but had not requested it.

The opposition Labour party said yesterday that meant senior ministers must have been involved.

Government ministers “need to explain who authorised the use of terrorism legislation in this case and what the justification was,” said lawmaker Yvette Cooper, the Labour spokeswoman on interior affairs.

Staff at the prime minister’s office said they would not comment on the Guardian allegations because it was an “operational matter”. GCHQ also declined to comment.

Reporter’s partner challenges detention

The partner of a journalist who broke stories on government electronic surveillance based on leaks from US whistleblower Edward Snowden is challenging the legality of his nine-hour detention at Heathrow airport, his lawyers said yesterday. They also protested police seizure of Brazilian David Miranda’s electronic equipment, demanded its return and said none of its data should be inspected, copied, disclosed or shared. Miranda, 28, was detained and questioned at the London airport at the weekend while travelling from Berlin to Brazil, where he lives with Guardian journalist Glenn Greenwald. Police called the detention “legally and procedurally sound,” but a lawyer at the firm representing Miranda said there was nothing legal about it. “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,” Kate Goold said.

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