A Malaysian airliner with 295 people on board has crashed in Ukraine on a flight from Amsterdam to Kuala Lumpur, amid allegations it was shot down.

Malaysia Airlines said it lost contact with Flight MH17 from Amsterdam over Ukraine.

Former ambassador to Russia Sir Tony Brenton told BBC News: "The assumption has to be Ukrainian rebels - who have shot down a number of Ukrainian military aircraft - may well have shot down this airliner, presumably by mistake."

The tragedy had "such potentially grave ramifications", he added, "it will have gone straight to Mr Putin".