The UK government has warned airlines not to allow an ex-CIA worker who leaked secret US surveillance details to fly to the UK.
The Associated Press news agency reported seeing a document at a Thai airport telling carriers to stop Edward Snowden, 29, boarding any flights.
The alert said he "is highly likely" to be refused entry to the UK, AP said.
Singapore Airlines told the BBC it was among airlines to receive the alert. The Home Office would not comment.
AP said the alert was issued on Monday by the Home Office's risk and liaison overseas network.
The agency said the document had a photograph of Mr Snowden, gave his date of birth and passport number and carried the words: "If this individual attempts to travel to the UK: Carriers should deny boarding."
It went on to warn airlines they may "be liable to costs relating to the individual's detention and removal" should they allow him to travel.
According to the Home Office website, a charge for such a situation would be £2,000 ($3,130).