Greenwald says police quizzed partner about his reporting
19 August 2013 Last updated at 05:53 BST
Brazil says the detention under British terror laws of one of its citizens at London's Heathrow airport caused "grave concern" and was "unjustified".
David Miranda, the partner of Guardian journalist Glenn Greenwald who published documents leaked by Edward Snowden, was held at Heathrow for nine hours on his way to Rio de Janeiro.
He reportedly had his mobile phone, laptop, DVDs and other items seized.
Speaking to the BBC Mr Greenwald said: "They spent the entire day asking about the reporting I was doing and other Guardian journalists were doing on the NSA stories."