The home secretary has expressed his concern at the loss of official papers believed to set out counter-terrorism plans for Heathrow Airport.

David Blunkett said that the mistake, which saw the documents found in a layby near the airport, was "very bad".

The Sun reported that the papers listed 62 sites from which a missile strike could be made at planes operating from the world's busiest airport.

Following the discovery the Metropolitan Police has launched an internal inquiry.

It was also reported by the newspaper that the documents included details about escape routes, evacuation plans and road closures.

"As far as I know this is a genuine document," Blunkett told BBC Radio 4's Today programme.

"The plans were obviously very good. Somebody disposing of them in a way that allowed that to happen is very bad."