The International Cycling Union (UCI) could take legal action to ensure that Alberto Contador can defend his Tour de France title in this year's event.
UCI president Pat McQuaid has condemned the Tour organisers' decision to ban Contador's Astana team following its history of doping scandals.
Spaniard Contador joined Astana when his Discovery Channel outfit disbanded.
"It would be a tragedy if Contador is not allowed to defend his title. It is a complete disgrace," McQuaid said.
"We will do all we can to ensure Contador rides in the tour."
"Why have they only selected Astana? It is unfair and unjustifiable"
Tour organisers announced that Astana would be excluded from the 2008 event, arguing that doping scandals that surrounded the team meant it could not be trusted.
But McQuaid argued that Astana were being unfairly singled out when other teams had a similar record, and were being used in a power struggle between Tour organiser ASO and the UCI.
He said: "They say that Astana damaged the Tour last year but so did other teams. So why have they only selected Astana? It is unfair and unjustifiable.
"In my opinion they have chosen Astana because of the relations between ASO and the UCI and because they don't want to respect our rules. It has nothing to do with the sport and everything to do with economics and power."
606: DEBATE
The UCI is keen for the three big multi-stage events - the Tour de France, Giro d'Italia and Tour of Spain - to be part of its ProTour series, which would guarantee places for elite teams.
But the organisers of the three big tours want to retain control over who can take part in their events.
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