Race director Christian Prudhomme said the investigation, in which 56 riders allegedly received given performance-enhancing drugs at a Madrid clinic, most likely won't conclude by the July 7 start of this year's tour.
"We reserve the right to take away riders' invitations - their names won't mean a thing," Prudhomme said Saturday. "We are prepared if riders that are not permitted to race want to take legal action."
"I wanted to send out this signal, I would have attended this presentation even if it had been held in Hong Kong, Paris or Berlin," Prudhomme added.
The raid on the clinic took place last May. Ullrich and Basso were among those forced out of last year's Tour de France. Basso has since been signed by the Discovery Channel team, a move criticized throughout the sport.
But none of the riders has been charged. The lead suspect, Spanish physician Eufemiano Fuentes, hasn't been indicted although he faces preliminary charges in Spain for crimes against public health.
Prudhomme said any evidence against the riders from Operation Puerto probably can't be used until after this year's tour.
"Cycling and the legal calendar don't fit together," Prudhomme said. "But there are facts emerging on an almost daily basis from the Fuentes case."