Elon Musk has revealed proposals for one of his most ambitious projects to date - intercontinental rocket flights for passengers that will take under half an hour.

The billionaire entrepreneur said the BFR spacecraft unveiled by his company SpaceX will be able to fly to most places on earth in under 30 minutes and anywhere in under an hour, with the cost roughly equivalent to an economy flight on a passenger jet.

The reusable rockets would apparently have a maximum speed of 27,000 km per hour (16,777 mph), although earth flights would travel at just over 7,000mph, allowing flights of thousands of miles in as little as 22 minutes.