Contador has consistently denied any involvement in doping

Contador is looking for a new team after Discovery Channel announced they would disband at the end of the season.

And he has been forced to defend himself from allegations linking him to the Operation Puerto blood doping case.

Spain coach Paco Antequera confirmed Contador would not ride in Stuttgart. "His head is elsewhere at the moment - he isn't ready to come back to racing."

At last year's World Championships, Paolo Bettini claimed the road race crown ahead of German Erik Zabel, with Spaniard Alejandro Valverde third.

Valverde's participation at this month's event is currently up in the air because of allegations about his involvement in Operation Puerto.

The International Cycling Union (UCI) recently said that the allegations against Valverde meant he would not be allowed to attend the championships.

However, the Spanish cycling federation has refused a UCI call to open an investigation into the Caisse d'Epargne rider.