A bold new design for the iconic red London bus has been unveiled by the Mayor of London in Britain's capital city.

The futuristic new design uses hybrid technology and is 40 percent more fuel efficient than the conventional diesel double deckers normally found on London's streets.

It will also reinstate the "hop-on hop-off" system that was commonplace on London's older buses, with an open platform at the rear as well as two sets of doors.

Inside, the bus features two staircases and a glass "swoop" that gives a light and airy feel for passengers.

"This iconic new part of our transport system is not only beautiful, but also has a green heart beating beneath its stylish, swooshing exterior," said London Mayor Boris Johnson.

"I expect to eventually have hundreds of these on London's roads, and for cities around the globe to be beside themselves with envy for our stunning red emblem of 21st century London."

The new buses are scheduled to enter service in early 2012.