The police will be asked to justify the detention of a Guardian journalist's partner under terror laws, the chairman of the Home Affairs Select Committee has said.
Keith Vaz said the full facts of David Miranda's nine-hour detention at Heathrow must be established quickly.
Miranda's partner is Guardian journalist Glenn Greenwald, who published documents leaked by whistleblower Edward Snowden.
"At 08:05 on Sunday 18 August 2013 a 28-year-old man was detained at Heathrow Airport under Schedule 7 of the Terrorism Act 2000. He was not arrested. He was subsequently released at 17:00," a Met police statement confirmed.
Police have not yet said why Mr Miranda was held, but did admit to his detention and quizzing by six agents.
Miranda was on his way from Berlin to Rio de Janeiro, where he lives with his partner, Glenn Greenwald, when he was stopped and detained.
"I remained in a room, there were six different agents coming and going, talking to me," Miranda said.
"They asked questions about my entire life - about everything. They took my computer, video game, mobile phone, my memory cards, everything."
He had been staying in Germany with US film-maker Laura Poitras, who has also been working on the Snowden files with Mr Greenwald and the Guardian, according to the newspaper.
He reportedly had his mobile phone, laptop, memory sticks, DVDs and other items seized before he was released.
Brazil has said that the detention of Brazilian national Mr Miranda caused "grave concern" and was "unjustified."
The Home Office said it was for the police to decide when to use its powers to stop people.
The Guardian said: "We were dismayed that the partner of a Guardian journalist who has been writing about the security services was detained for nearly nine hours while passing through Heathrow airport."
Under schedule 7, UK police can hold someone at an airport for up to nine hours for questioning about whether they have been involved with acts of terrorism.
Anyone detained must: "Give the examining officer any information in his possession which the officer requests." Any property seized must be returned after seven days.
Greenwald said the British authorities' actions in holding Miranda amounted to "intimidation and bullying" and linked it to his writing about Edward Snowden's revelations concerning the US National Security Agency (NSA).
"They never asked him about a single question at all about terrorism or anything relating to a terrorist organisation," he told the BBC.
"They spent the entire day asking about the reporting I was doing and other Guardian journalists were doing on the NSA stories.
"The principal point, since they kept him for the full nine hours, is to try and send a message of intimidation and bullying."
He added: "I don't understand why they don't realise that all it's going to accomplish is the exact opposite effect - I'm going to report more aggressively and with a more emboldened mind."
Webroot provides industry leading security solutions for consumers, enterprises and small and medium businesses worldwide.
The Neverfail Group is dedicated to creating a world where business applications are continuously available. High Availability, Disaster Recovery...
Absolute® Software specialises in technology and services for the management and security of mobile computers and smartphones.
Capscan is a leading supplier of international address management solutions and data integrity services. Capscan has more than 1800 customers...