Nine ProTour teams have demanded immediate talks with the organizers of cycling's three grand tours after the Giro d’Italia denied entry to four of their number.

Though the 18 ProTour teams are supposed to be included in the season's major races, Astana, Team High Road, Bouygues Telecom and Crédit Agricole all were denied invitations to the Giro in the wake of a dispute between major race organizers and the UCI.

The Giro, Tour de France and Vuelta a España – as well as other races owned by the trio's respective management companies - are no longer part of the ProTour following disagreements over the way the UCI series is run, and the organizers now have the upper hand when it comes to choosing teams for their races.

But with concerns growing over their participation in the big events, half of the 18 ProTour teams are now considering drastic action.

"We understand and respect the organizers' desire to avoid the presence of teams that could damage the image of the sport," said a statement from the group. "However, we don't want to come to a situation where we are forced to apply pressure by saying, 'Either you take all of us or none of us.’"

Some prominent teams are involved in this move, including the Quick Step team of world champion Paolo Bettini as well as Lampre, Saunier Duval, Liquigas, Milram, Rabobank, High Road, CSC and Astana, now home to 2007 Tour champ Alberto Contador.

Kazakhstan's Alexandre Vinokourov and the whole Astana team were kicked off the Tour de France last year after he tested positive for blood doping.

After initially citing that incident as one of the reasons not to invite Astana to the May 10-June 1 race, Giro chief Angelo Zomegnan said Monday his decision was more to do with the quality of riders the Kazakh-backed team would likely send.

"At this moment, the quality of the proposed participating riders for the Giro is not in proportion to the potential of the team," said Zomegnan. "I do not take into consideration what happened with the old Astana in the past. Time probably cures all things."

Astana, now registered in Luxembourg, has new management and new riders, and has promised to introduce a comprehensive internal anti-doping program under former Discovery Channel chief Johan Bruyneel.

But Contador - who despite being cleared by a Spanish judge continues to be linked to the Operación Puerto doping scandal - has not been guaranteed a chance to defend his title in this year’s Tour.