The T-Mobile team has suspended all Ullrich, teammate Oscar Sevilla and team manager Rudy Pevenage.

Organisers of the Tour, which starts in Strasbourg on Saturday, have now excluded basso.

All four denied any wrongdoing when allegations first began to emerge earlier this week.

Following the first reports of the scandal emanating from Spain, T-Mobile management asked all its riders to sign written declarations stating that they were not involved in any way.

Team manager Olaf Ludwig said: "We talked to the riders several times and even have their declarations of innocence in written form.

"At first we had no reason to doubt the riders' statements, but that situation has now changed profoundly."

Ullrich and Basso are unlikely be the last big names to be suspended from the Tour de France after organisers ASO (Amaury Sport Organisation) revealed that they have been given a list of more than 50 riders involved in the probe.

A six-month doping investigation in Spain, nicknamed Operation Puerta, led to the arrests of five men, including Manolo Saiz, who recently resigned as boss of the Liberty-Seguros team.

ASO spokesman Philippe Sudres said: "The Spanish Ministry of Sport handed the file to the cycling federation who passed it on to UCI and Tour organisers."

If it's your own blood why is it cheating?

The current scandal is the biggest doping controversy to hit the sport since the Festina affair rocked the 1998 Tour.

Ullrich, the 1997 winner, had been among the favourites for this year's Tour.

In addition to his win in 1997, the German has been runner-up five times and was third last year.

CSC rider Basso, who recently won the Tour of Italy, has finished on the podium of the Tour for the last two years.

Italy's Lorenzo Bernucci and Germany's Stephan Schreck will now replace Ullrich and Sevilla in the T-Mobile team.