An Oxfordshire team has designed a hypersonic passenger aeroplane that could one day fly passengers between Europe and Australia in less than five hours.

The A2 aeroplane, designed by Culham-based Reaction Engines with funding from the European Space Agency, would carry 300 passengers at a top speed of almost 4,000mph.

The company says the aircraft could be operating within 25 years and ticket prices would be comparable with an existing business class ticket, currently about £3,500.

The Lapcat (Long-Term Advanced Propulsion Concepts and Technologies) project is being funded by the European Space Agency to encourage companies to push the boundaries of commercial air travel using technology more commonly associated with space flight.

Reaction Engines says the A2 would be capable of sustained travel at Mach 5, or 3,800 mph, more than twice the speed of Concorde.

At 143 metres long it would be roughly twice the size of the biggest current jumbo jets.

It would run on a liquid hydrogen engine Reaction Engines is developing based on existing technology.

Managing director Alan Bond said the next step was to research the environmental effects the aircraft would have.

He added: "There is a market for an aeroplane like this but there are still a lot of questions we have to answer."

He told The Guardian that the A2 would fly quietly and subsonically from Brussels out into the north Atlantic at Mach 0.9 before reaching Mach 5 across the North Pole and heading over the Pacific to Australia.

The flight time, allowing for air traffic control, would be four hours 40 minutes.

The space agency's website says that hypersonic flight is generally considered to begin at Mach 5, when aerodynamic heating becomes important in aircraft design, with temperatures on the surface of a plane reaching 1,000C.

Hypersonic flight is not new.

The first man-made object to reach hypersonic speeds was an American rocket, assembled from a captured German V-2 in 1949.

Astronauts and cosmonauts have all reached hypersonic speeds on their way into orbit in space.

But current research focuses on sustained hypersonic flight within the Earth's atmosphere.

Where Nasa's Space Shuttle uses the thrust of its engines to fight the force of gravity, a hypersonic vehicle would use the aerodynamic lift generated on its wings and fuselage.