The US says it was tipped off by Britain that it planned to detain the partner of a Guardian newspaper's journalist.

Glenn Greenwald has written stories based on documents leaked by former National Security Agency contractor Edward Snowden. London police detained David Miranda, who is in a civil union with reporter Glenn Greenwald, for nine hours under anti-terror legislation at Heathrow airport on Sunday.

Josh Earnest, Wgite House Spokesman, said, "There was a heads-up that was provided by the British government, again this is something we had an indication this was likely to occur, but it was not something that we requested and it¡¯s something that was done specifically by the British law enforcement officials there."