It is due out in 1999, timed to take over from the original after 40 years in production.

The new Mini will be nine inches longer, three inches wider and two inches taller, according to motoring magazine Autocar.

Work started in January under the heaviest security but this week Autocar claims exclusive details of the car.

But other manufacturers have their eyes firmly fixed on the mini car scene.

The biggest challenge is likely to come from Ford which has given the go-ahead for a car that has a shape as strange as its name. The Ka will be built at Ford's Spanish factory.

Rover's policy is not to discuss its future model programme but Autocar's inside information uncovers a Mini that's bigger, fraster, safer . . . and more fun.

It will be every bit as cheeky and loveable as the celebrated star of the brilliant film, the Italian Job, says Autocar.

Rover chief executive John Towers calls the project "a classiic example of what we're about these days.''

He said: "I have given strong indications on a number of occasions that we value the Mini marque and we recognise the heritage and tradition of the product.

"We are in a unique position because no one else can do a Mini but I'm not going to confirm what we are doing or when we might do it.''

The new Mini will have up-to-date mechanical parts but classic Mini touches - such as round headlamps - will remain.

"It's a hugely important car and quite clearly the most significant of the city cars currently on the drawing boards,'' says Michael Harvey, Autocar's editor.

"With the full force of Rover and BMW behind the project, it will undoubtedly be successful.''

The new car is said to beno less radical than the original 35 years ago.

Rover's chairman Bernd Pischetsrieder, says he is not interested in "building just another small car''.

He has good reason, for his great uncle, the late Sir Alec Issigonis was the genius whose drawings on the back of a cigarette packet were transformed into a car which changed the thoughts of car designers.

There has been much discussion about the future of the Mini, particularly following the takeover of Rover by German car giant BMW.

BMW and Rover have set about bringing together as many members of the original team as possible, including 78-year-old Dr Alex Moulton, the Mini's suspension engineer.

The Mini is just one of a number of ventures being worked on by Rover and other names from the past, such as Riley, Healey and Triumph, may reappear.