LONDON: British authorities faced increasing pressure on Monday to explain why they used anti-terror laws to detain the partner of a journalist who worked with US intelligence leaker Edward Snowden.

David Miranda — the Brazilian partner of Glenn Greenwald, an American journalist with Britain's Guardian newspaper — was held for almost nine hours on Sunday as he passed through London's Heathrow Airport on his way to Rio de Janeiro from Berlin.

A furious Greenwald said British authorities had “zero suspicion” that Miranda was involved in terrorism and instead spent hours questioning him about the Guardian's reporting on the activities of the US National Security Agency, which has enraged Washington.

“This was obviously designed to send a message of intimidation to those of us working journalistically on reporting on the NSA and its British counterpart, the GCHQ (Government Communications Headquarters),” Greenwald wrote in the Guardian.

“They completely abused their own terrorism law for reasons having nothing whatsoever to do with terrorism.” Miranda, 28, often assists Greenwald with his work, the Guardian said. He is not an employee of the newspaper but it had paid for his flights. He had stayed in Berlin with Laura Poitras, a US film-maker who has been working with the Guardian. Miranda said he had been questioned by six agents at Heathrow who confiscated his electronic equipment.

“They asked questions about my entire life, about everything,” he said in comments published by the Guardian. “They took my computer, video game, mobile phone, my memory card.” A spokesman for Prime Minister David Cameron said the British government takes “all necessary steps to protect the public from individuals who pose a threat to national security”. “But it is for the police to decide when it is necessary and proportionate to use these powers,” the spokesman said.

But authorities were under increasing pressure to explain why he had been held, with Brazil expressing “grave concern” that one of its citizens had been apparently “held incommunicado”.

Britain's opposition Labour party called for an urgent investigation into whether anti-terror laws had been misused.

“Any suggestion that terror powers are being misused must be investigated and clarified urgently,” said Yvette Cooper, Labour's home affairs spokeswoman. Britain's independent reviewer of terror legislation, the barrister David Anderson, said he had asked for a briefing on what he described as an “unusual”case.

London's Metropolitan Police confirmed that a 28-year-old man was detained at Heathrow Airport under anti-terrorism legislation. “He was not arrested. He was subsequently released,” a spokesman said.

Brazil's foreign ministry said its embassy in London had contacted British officials prior to Miranda's release and that Brazil would also be seeking an explanation.

“This measure is without justification since it involves an individual against whom there are no charges that can justify the use of that legislation,” the ministry said in a statement.

REVENGE TACTICS: Greenwald, a well-known journalist in the United States, analysed and published information on documents released by former US security contractor Snowden revealing huge electronic surveillance operations by the NSA.

Snowden has been granted asylum in Russia after spending five weeks in limbo at a Moscow airport attempting to avoid extradition to the US. He is wanted by Washington on espionage charges.

The Guardian said it was “dismayed” by Miranda's detention and was seeking “clarification” from the British authorities.

Arriving to meet Miranda at Rio's airport, meanwhile, Greenwald said he was now even more determined to continue reporting on the intelligence leaks — with a new focus on Britain.

“I have many more documents to report on, including ones about the UK, where I'll now focus more,” he told reporters.

“I will be more aggressive, not less, in reporting.” British authorities would “come to regret” detaining Miranda, he warned.

Rights group Amnesty International said Miranda was “clearly a victim of unwarranted revenge tactics”, while Reporters Without Borders said it was “outraged” by his detention. “The world's most repressive states often identify journalism with terrorism and now the British authorities have crossed a red line by resorting to this practice,” the group said.—AFP