LONDON (AP) — A British lawmaker says he will ask police to explain why the partner of a journalist who received leaks from former National Security Agency contractor Edward Snowden was detained for nearly nine hours at Heathrow Airport.

Keith Vaz, the chairman of the Home Affairs Select Committee, says he wants to know why police stopped David Miranda, the partner of Guardian journalist Glenn Greenwald.

Miranda was stopped Sunday while traveling home to Brazil after visiting Germany where he met with Laura Poitras, a U.S. filmmaker who has worked with Greenwald on the NSA story. The Guardian reported it paid for Miranda's flights.

Greenwald has written about NSA surveillance programs based on files disclosed by Snowden, who now has temporary asylum in Russia.