LONDON/BERLIN/MOSCOW: Britain's deputy prime minister says the government ordered the country's top civil servant to ask the Guardian newspaper to destroy data leaked by former National Security Agency contractor Edward Snowden.

Nick Clegg defended the decision to ask Cabinet Secretary Jeremy Heywood to approach the newspaper, which began publishing stories in June based on Snowden's leaks.

Clegg said Wednesday that it was a reasonable request because the material would represent a threat to national security should it fall into the hands of terrorists.

The Guardian says it destroyed hard drives containing material leaked by Snowden rather than hand it over or face legal action from the government. The paper says it has other copies of the material outside Britain.

British Prime Minister David Cameron ordered his top civil servant Heywood to try to stop revelations flowing from the Guardian newspaper about US and British surveillance programs, two sources with direct knowledge of the matter said, according to Reuters.

Government supporters say information leaked by Snowden, who has obtained asylum in Russia, could threaten national security. However, rights groups have accused the government of an assault on press freedom over a series of incidents. These include the detention of a Guardian reporter's partner, David Miranda, and news that the paper had been forced to destroy computer files containing information from Snowden under threat of government legal action.

Miranda was held for nine hours on Sunday under an anti-terrorism law at Heathrow airport, where he was in transit on his way from Germany to his native Brazil.

He was released without charge minus his laptop, phone and memory sticks. He had been ferrying documents between Greenwald and a Berlin-based journalist contact of Snowden.

Brazil has said Miranda's detention had "no justification," while Miranda has launched legal action against the police and the government, accusing them of abusing anti-terrorism powers to get hold of sensitive journalistic material.

Home Secretary Theresa May, the British interior minister, said on Tuesday police were right to detain Miranda if they thought he was "in possession of highly sensitive, stolen information that could help terrorists, that could risk lives."

Germany's top human rights official on Wednesday sharply criticized a British crackdown on the Guardian newspaper over its publication of US security secrets leaked by Edward Snowden.

Markus Loening, the rights chief at the Foreign Ministry, expressed "great concern" about media freedom in Britain after the Guardian said it was forced to destroy files linked to US surveillance practices or face a court battle.