Claims that the seized David Miranda UK Intelligence material 'could endanger lives'

David Miranda with journalist Glenn Greenwald at an airport in Brazil.

A witness statement given to the high court today as part of the legal discussion surrounding David Miranda, the partner of Guardian journalist Glenn Greenwald, claims that the information seized by the police contains information which could directly endanger lives.

The statement from Oliver Robbins, the Deputy National Security Adviser for Intelligence, Security and Resilience in the Cabinet Office, describes why the government believes it is essential to retain and examine the material seized from Mr Miranda.

He tells the court that he believes Mr Miranda was carrying as many as 58,000 documents on the external hard drive that was seized during his arrest. These contain Secret and Top Secret UK intelligence and so far the authorities have only been able to access a very limited number of them. The files are encrypted but he reveals that Mr Miranda was carrying with him a piece of paper containing basic instructions for accessing some of the data. Much of their remaining material staff at GCHQ are still working on and Mr Robbins says that this is taking " a considerable amount of time and consuming a large amount of resources".

He tells the court in his 13 page statement that: "I can say with confidence …that the material seized is highly likely to describe techniques which have been crucial in life-saving counter terrorist operations and other intelligence activities vital to UK national security. The compromise of these methods would do serious damage to UK national security and ultimately risk lives."

Mr Robbins goes on to claim that it was a, "particular concert for Her Majesty's Government that the identity of a UK intelligence officer might be revealed." Adding, "that contained in the seized material are personal information that would allow staff to be identified, including those deployed overseas."

"I am advised that the information that has already been obtained has had a direct impact on decision taken in regard to staff deployments and is therefore impacting operational effectiveness."

He says that the government believe that Edward Snowdon and Glenn Greenwald have the ability to download bulk material from the websites or networks and therefore "far from undertaking targeted and careful appropriation of classified material, Mr Snowden indiscriminately appropriated material in bulk."

They assert that neither Mr Greenwald or The Guardian have shown good judgement about what should be disclosed and they give a long explanation about why they ordered the destruction of hard drives at the newspaper.