The announcement is part of a package of measures to prevent any repetition of this year's doping scandal, when one third of all teams either withdrew or were expelled because of illegal drug abuse.

Entrants will have to sign a new code of conduct which stipulates that any team or individual suspected of using performance-enhancing drugs will be suspended from the Tour.

Dope tests will be conducted by the French sports ministry.

Race organisers have also shortened the course by about 200km, making it less gruelling.

The 1999 Tour will be about 200km shorter

But that has prompted champion Marco Pantani to say he may not enter in 1999, as the race looks too easy.

Pantani said he was particularly concerned that there will now be less hill cycling at the event.

"It's not a course to my liking," Pantani said on Thursday night.

"There's too much against-the-clock racing."

Organisers of the prestigious race had unveiled the route for next year's 20-stage event earlier in the day.

They said the Tour's popularity "remains intact" despite last year's troubles. intact".

The scandal which rocked this year's Tour broke before the 11 July start in Dublin.

By the end of the three-week race in Paris the field had been decimated by disqualifications and withdrawals.

Marco Pantani: Fears next year's course will not be hard enough

"Now, the Tour de France Company reserves the right to refuse entry up to the start to any rider or team which might damage the image of the race, notably through doping," said organiser Jean-Marie Leblanc.

Teams must adhere to a charter of ethical and sporting behaviour. The top 16 teams in the rankings qualify automatically, with another four invited.

Jean-Claude Killy, president of the Tour Company, said: "[The riders] are more victims than guilty. But now they won't any longer be able to say they knew nothing.

"We refuse to believe doping is something you have to live with and we will be strict over our rule of conduct and on the moral guarantees of those who wish to come on this Tour."

French cycling federation president Daniel Baal applauded the efforts to help rid the sport of drugs.

"In the current circumstances, only strong and clear decisions are going to allow cycling to enter a new era," he said.