http://www.bbc.com/news/world-us-canada-28185149

"American officials have ordered some overseas airports with direct flights to the US to intensify screening of electronic devices.

Transport officials said in a statement passengers could be asked to switch on devices, and equipment that does not power up would not be allowed on board.

An official told the BBC that London's Heathrow was among the airports.

The US announced new security measures last week, apparently in response to a terror threat, but gave no details."

"The UK, France and Germany have all said they would comply with the American demands."