BASEL, Switzerland  - World cycling's governing body the UCI is preparing a formal complaint to the European Commission about the organisers of the three big Tours -- the Tour de France, the Giro d'Italia and the Tour of Spain.

The trio, known as the Grands Tours, broke ranks with the UCI last month to set their own conditions for participation outside the UCI's ProTour circuit.

They said that they wanted to return to a "more open sporting model."

The UCI said on its Web site (www.uci.ch) on Tuesday: "The organisers of the Grands Tours have acted as a cartel in order to protect their own dominant position in the field of professional road cycling."

The ProTour, open only to elite teams, started in 2005 with 30 races, including the big three Tours.

The initiative has been plagued by disagreements between the UCI, the big Tours, teams and national federations.