LONDON - Virgin Galactic reveals designs of 2,300mph supersonic jet that would fly from London to New York in 90 minutes.

Virgin Galactic has revealed designs for a supersonic passenger plane capable of flying three times the speed of sound.

With a top speed of around 2,300mph (3,700kmh), it could fly from London to Sydney in just five hours - or to New York in less than two.

Virgin has teamed up with engine-maker Rolls-Royce to work on the concept, which is still in the early stages.

The delta-wing jet would cruise at above 60,000ft (18,300m), far higher than current passenger planes, but would only have room for nine to 19 passengers.

The project is separate from Virgin's bid to send customers to the edge of space to experience weightlessness - which has already completed a number of test flights using the SpaceshipTwo craft.

Supersonic passenger flights stopped when Concorde retired in October 2003 and no one has so far plugged the gap for ultra-fast air travel.

Virgin said it had signed a memorandum of understanding with Rolls-Royce "to collaborate in designing and developing engine propulsion technology for high speed commercial aircraft" and has also worked with NASA on the concept.

The company said the Mach-3 jet would target existing long-distance commercial routes, taking off and landing normally at existing airports.

The next phase will look at things such as which materials to use, how to reduce noise and emissions, and how to keep the jet cool as it flies supersonically.

US aviation regulator the FAA has also agreed to help work on a certification framework for the plane.

Other companies are also targeting a new age of super-fast air travel.

They include aerospace giant Lockheed-Martin, and US start-up Boom Supersonic - which is set to reveal a scaled-down prototype this winter followed by test flights in 2021.

Up to 19 passengers will fit on one of the high-tech planes, though no date has been set for a maiden voyage – or even a test flight.