What did Theresa May know and when did she know it? Labour demands answers over Miranda

Labour stepped up its attack on the Home Office over the nine-hour detention of David Miranda today, as the international row escalated.

With the political response growing more urgent, numerous new developments emerged, including:

  • Legal action was taken against the Home Office
  • The UK ambassador to Brazil was summoned by the country's foreign minister
  • The editor of the Guardian revealed that government officials had forced the newspaper to destroy hard drives
  • Scotland Yard moved to justify the action it took over the Brazilian citizen
  • The White House admitted it had been given a "heads up" about the detention

"If the White House knew about the decision to detain David Miranda at Heathrow, surely the home secretary knew too?" Labour shadow home secretary Yvette Cooper said.

"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."

The legal battle over Miranda's detention started up this afternoon, when legal firm Bindmans sent a letter demanding to know at whose request, and for what purpose, police seized his property.

Solicitor Gwendolen Morgan demanded that "there will be no inspection, copying, disclosure, transfer, distribution or interference, in any way" with the disputed information until the case has been determined by the court.

She said: "Our client is entitled to undertakings that journalistic material which has been seized unlawfully will not be disclosed or shared or used.

"The apparently cavalier way in which journalistic privileges have been breached is extremely troubling."

Bindmans has applied for an injunction and asked the court to consider the judicial review as a matter of urgency this week.

Meanwhile, London relations with Rio de Janeiro hit a new low, amid continued recriminations over the detention of the Brazilian citizen.

"There is no justification for a Brazilian citizen who is not suspected of involvement with terrorism or any other illicit activities to be detained incommunicado for nine hours," Brazilian foreign minister Antonio Patriota said at a press conference overnight.

"We acknowledge counter-terrorism is a legitimate fight to prevent the loss of innocent lives, but it also must be based on the ideals of multilateralism, international law and rationality."

The strongly-worded statement from the Brazilian foreign minister did not pacify Miranda, who has been issuing ever-tougher condemnations of his treatment, along with partner Glenn Greenwald.

The pair told local daily O Globo they wanted more from the Brazilian government than a statement and Greenwald vowed to embarrass "England" with his journalistic work.

Meanwhile, Guardian editor Alan Rusbridger revealed that senior government officials "claiming to represent the views of the prime minister" had demanded he cease publishing details of UK surveillance operations emerging from Edward Snowden, a former CIA analyst who has been granted asylum in Russia.

Rusbridger said government officials threatened to force the surrender of the materials the stories were based on.

"And so one of the more bizarre moments in the Guardian's long history occurred – with two GCHQ security experts overseeing the destruction of hard drives in the Guardian's basement just to make sure there was nothing in the mangled bits of metal which could possibly be of any interest to passing Chinese agents," he said.

Kirsty Hughes, chief executive of Index on Censorship, commented: "Using the threat of legal action to force a newspaper into destroying material is a direct attack on press freedom in the UK.

"It is unclear which laws would have been used to force the Guardian to hand over its material but it is clear that the Snowden and NSA story is strongly in the public interest."

Scotland Yard finally released a statement defending its use of schedule seven of the Terrorism Act 2000, which allows authorities to hold terror suspects for up to nine hours without "reasonable suspicion".

Miranda was held for the full time limit – a highly unusual development.

"The procedure was reviewed throughout to ensure the examination was both necessary and proportionate," it said.

"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."

The Home Office also aggresively defended the action.

"The government and the police have a duty to protect the public and our national security," a spokesperson 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."

Downing Street has insisted the decision to detain Miranda was an operational matter for police, but a comment from the White House saying they had been notified raised questions about the British account.

"There was a heads up that was provided by the British government," Josh Earnest, principal deputy White House press secretary, said at the daily briefing.

"This is something that we had an indication was likely to occur but it is not something that we requested. It was something that was done specifically by the British law enforcement officials.

"This is an independent British law enforcement decision that was made."

The alert to the Americans strongly suggests Downing Street or Home Office involvement.

"I find it wholly implausible that the Metropolitan Police would have taken such a decision and somehow notify the White House but not notify the home secretary," former shadow home secretary David Davies told the Guardian.

"The government has to say what was going on here. We are a country where freedom of speech and freedom of movement are fundamental and that is never more true when you are talking about journalists holding the light up to the actions of government."

The independent reviewer of terrorism legislation, David Anderson, has raised concerns over the "unusual" length of the detention and is today meeting with police to discuss the matter.

The QC is usually supportive of counter-terror measures and is not a critic of the controversial powers handed to authorities by schedule seven, but he has been unusually outspoken in his comments about the Miranda detention.

"The police, I'm sure, do their best," he told Radio 4.

"But at the end of the day there is the Independent Police Complaints Commission, which can look into the exercise of this power, there are the courts and there is my function."

Miranda had been staying in Germany with US filmmaker Laura Poitras and was in the process of "ferrying materials" between her and his partner Greenwald in Brazil, where they both live.