Cycling's international governing body, the UCI, on Saturday upheld its earlier decision to exclude Spain’s Alejandro Valverde from the World Cycling Championships in Stuttgart at the end of the month.

The announcement comes after the Spanish cycling federation openlydefied the UCI by registering Valverde for the championships.

Valverde's participation at the event on September 25-30 had been up in the air because of growing suspicions over his alleged links to the Operación Puerto doping affair in Spain.

Operación Puertoerupted in May 2006 after police raided the premises of Spanish doctor Eufemiano Fuentes, recovering bags of stored blood and banned doping substances.

On August 29, the UCI officially asked the Spanish federation to opendisciplinary proceedings against Valverde for his suspected involvement in Operación Puerto.

A UCI spokesman said on Saturday that according to its rules, any rider who is officially the subject of an anti-doping investigation cannot compete in the world championships.

"This inquiry does not in any way imply that Alejandro Valverde is guilty," noted the UCI, claiming his exclusion was based on protecting the organization and reputation of the world championships.