A Canadian coin, nicknamed the "big maple leaf", with a face value of $1m, has been stolen from a museum in Berlin, Germany.

The coin, that weighs 100kg (220lb) and is made of pure 24-carat gold, is worth $4m (£3.2m).

Police are still trying to work out how the thieves made off with their single piece of loot, which was protected by bulletproof glass.