British authorities faced a furor on Monday after they held the partner of a journalist who worked with Edward Snowden to expose US mass surveillance programs for almost nine hours under anti-terror laws.

David Miranda, a Brazilian citizen and partner of US journalist Glenn Greenwald who writes for Britain's Guardian newspaper, was not charged with any crimes, a report on the Guardian website said.

A British Metropolitan Police Service spokesman said a 28-year-old male had been detained at London's Heathrow Airport under provisions of the 2000 Terrorism Act. That law gives British border officials the right to question someone "to determine if that individual is a person concerned in the commission, preparation or execution of acts of terrorism".

Rio de Janeiro-based Greenwald has interviewed Snowden and used 15,000 to 20,000 documents that Snowden passed to him to reveal details of the US National Security Agency's surveillance methods.

A furious Greenwald said British authorities had "zero suspicion" that Miranda was involved in terrorism and instead spent hours interrogating him about The Guardian's reporting on the activities of the NSA, 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," Greenwald wrote in The Guardian.

"They completely abused their own terrorism law for reasons having nothing whatsoever to do with terrorism."

Miranda had been refused access to a lawyer and officials had taken his laptop and mobile phone, Greenwald added.

The British interior ministry did not immediately comment on Miranda's detention, saying it was a police matter.

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" at the airport.

Keith Vaz, chairman of the British parliament's home affairs committee, said he was writing to the police to demand an explanation, describing Miranda's detention as "extraordinary".

"They may have a perfectly reasonable explanation," he told BBC radio.

"But ... if we are going to use the (Terrorism) Act in this way, for those issues that are not related to terrorism, then at least we need to know."

AFP-Reuters

(China Daily 08/20/2013 page10)