Files seized from David Miranda while he was held under an anti-terrorism statute on August 18 could have endangered British agents, British Deputy National Security Adviser Oliver Robbins claimed Friday.
The BBC reports that the government said one of the files contained over 58,000 "highly classified UK intelligence documents." Miranda's lawyers, meanwhile, disputed their statements as "sweeping and vague."
Miranda, 28, is the partner of American journalist Glenn Greenwald, who was at the forefront of exposing government spying programs revealed through the leaks of former NSA contractor Edward Snowden. He was detained in the Heathrow Airport while en route to his home in Brazil from Germany, where he visited with Greenwald's reporting partner Laura Poitras. During a nine hour interrogation — the maximum allowed under schedule 7 of the Terrorism Act 2000 — Miranda was reportedly threatened with legal action and denied access to an attorney.
Greenwald, who writes for The Guardian, lives in Rio de Janiero because for many years the United States government did not recognize his relationship with Miranda for immigration purposes, while Brazil's did.
During the interrogation, British authorities seized a variety of electronic devices from Miranda, including a cell phone, a laptop, thumb drives, and a game console. The data on the devices was heavily encrypted.
Now, British authorities are saying that Miranda carried the key to the encryption with him on a scrap of paper, which allowed them to access some of the information. They also would not go into detail on the exact nature of the threat posed by the files.
Miranda's legal team disputes the British government's accusations. According to CNN, the "law firm Bindmans, which is representing Miranda, said the Home Office and police had made "sweeping assertions about national security threats" in their court filing but given no details to back up the claim."
Miranda "does not accept the assertions they have made and is disappointed that the UK Government is attempting to justify the use of terrorist powers by making what appear to be unfounded assertions," a statement from the law firm said.
Greenwald took to Twitter on Friday to rebut the accusations.
Last week, Miranda's legal team won a temporary injunction from Britain's High Court, which ruled that the information carried by Miranda could only be studied for the purpose of protecting national security.