David Miranda

David Miranda's detention at Heathrow airport violated his human rights, the High Court has heard.

Gwendolen Morgan of Bindman Partners said in a witness statement made on behalf of Miranda that Schedule 7 of the Terrorism Act was used "for an improper purpose and was therefore unlawful".

The decision to use it "amounted to a grave and manifestly disproportionate interference" with Miranda's human rights, Morgan said.

David Miranda's lawyer said he was taking legal action because the Home Office and police had refused to provide assurances they would not share files seized on Miranda's laptop.

Matthew Ryder QC told judges the Home Secretary and the commissioner of the Metropolitan Police had failed to give undertakings "protecting the confidentiality of sensitive journalistic material".

"That is why we are here now," Ryder said at London's High Court.

Miranda, the partner of Guardian journalist Glenn Greenwald, has launched an application for judicial review over his detention at Heathrow airport under the Terrorism Act.

Lawyers acting for the partner of a journalist held for nine hours under anti-terror laws will take his case to the High Court.

They have applied for an injunction preventing the police or government using, copying and sharing data from electronic devices seized from David Miranda during his detention.

Two judges will also hear their argument that Mr Miranda's detention at Heathrow Airport was a misuse of Schedule 7 of the Terrorism Act 2000 and breached his human rights.

Lawyers acting for the partner of a journalist held for nine hours under anti-terror laws will take his case to the High Court tomorrow.

They have applied for an injunction preventing the police or government using, copying and sharing data from electronic devices seized from David Miranda during his detention.

Two judges will also hear their argument that David Miranda's detention at Heathrow Airport was a misuse of Schedule 7 of the Terrorism Act 2000 and breached his human rights.

Mr Miranda is the partner of Guardian journalist Glenn Greenwald who has worked with US whistleblower Edward Snowden on a series of security services exposes.

He was held without charge for the maximum time permitted under the anti-terror legislation as he changed planes on a journey from Berlin to his home in Brazil.

Read: Guardian journalist 'angry' over 'thuggish' detention of partner David Miranda

Keith Vaz, chair of the Home Affairs Select Committee, has said the actions of Cabinet Secretary Sir Jeremy Heywood over material held by The Guardian was "unprecedented" and called for a full statement from David Cameron to explain the government's involvement in the incident:

Home Secretary Theresa May told BBC Radio 4's The World At One that it was right that senior members of the government have been involved in the Snowden leaks affair in recent days.

She said: "Issues of national security are rightly addressed at an appropriate level within government.

"I do not find it surprising somebody at a very senior level within government should be involved in this particular issue.

"I think it is right and proper the government had those discussions with the Guardian, that the action that was taken was taken.

"If government believes information that could be of help to terrorists is potentially being held insecurely, could fall into the wrong hands, I think it is right the government should act.

"I don't find it strange that should be done at a senior level."

Nick Clegg has backed the decision to send top civil servant Sir Jeremy Heywood to the Guardian and urge them to destroy classified data because it was "preferable" to taking legal action.

David Cameron directed Sir Jeremy to contact the newspaper about classified material handed over by Edward Snowden.

The Deputy Prime Minister's spokesman said: "(Clegg) thought it was reasonable for the Cabinet Secretary to request that the Guardian destroyed data that would represent a serious threat to national security if it was to fall into the wrong hands.

"The Deputy Prime Minister felt this was a preferable approach to taking legal action. He was keen to protect the Guardian's freedom to publish, whilst taking the necessary steps to safeguard security.

"It was agreed to on the understanding that the purpose of the destruction of the material would not impinge on the Guardian's ability to publish articles about the issue, but would help as a precautionary measure to protect lives and security."

Watch: Greenwald tells ITV News he is 'angry' over 'thuggish' detention

Watch: Greenwald tells ITV News 'not a single comma' from his reports has helped terrorism

The partner of a Guardian journalist, who wrote a series of stories on the US National Security Agency's mass surveillance, said he was forced to reveal his social media and email passwords while detained at Heathrow Airport.

David Miranda told the BBC he was threatened with imprisonment if he did not comply with his interrogators requests.

The Brazilian, who is the partner of reporter Glenn Greenwald, said disclosing his passwords made him feel as if he was "naked in front of a crowd".

Watch: Greenwald tells ITV News he is 'angry' over 'thuggish' detention

Watch: Greenwald tells ITV News 'not a single comma' from his reports has helped terrorism

Cabinet Secretary Sir Jeremy Heywood was directed by the Prime Minister to contact the Guardian about the classified material handed over by Edward Snowden, it has been reported.

The intention was to spell out the serious consequences of continuing to publish material about UK and US intelligence operations, the Independent said.

Earlier, Guardian editor Alan Rusbridger revealed his newspaper had destroyed a hard drive containing a copy of the secret documents under the supervision of GCHQ officers following sustained pressure from Government.