Three-time Vuelta a España winner Roberto Heras, whose two-year suspension for doping ended in October, confirmed Saturday that he has decided to quit professional cycling.

"I've thrown in the towel, there's no going back," Heras, 33, told the Spanish sports daily Marca.

Heras said he has received several offers from European continental teams, but remains frustrated because he is still barred from joining a ProTour-level team for another two years. The UCI ProTour code of ethics prevents riders from being hired by top-level teams for a period double that of their original suspensions.

"I still don't understand the code of ethics and why ProTour teams can't hire a rider who like me has served his ban,” Heras said. “Other top riders will have to quit the peloton because they can't find a team.

"Cycling is going through a bad period: teams, organizers, the UCI are at war, there is no unity, so it's very difficult to get out of the crisis."

Heras was suspended for two years in October 2005 after testing positive for the banned blood-booster EPO in samples taken after the penultimate stage of the 2005 Vuelta a España. He was leading the race at the time and went on to what was apparently his fourth Vuelta victory in Madrid the next day. He was subsequently stripped of the title and Rabobank’s Denis Menchov was named the winner.

Menchov held the leader's jersey for more than a week that year, winning two stages and finishing 4:36 behind Heras. He won the 2007 Vuelta outright.

Heras had said in the past that he was planning to return to the sport after completing his ban, but told Marca that he is frustrated by the continuing ProTour ban.

Heras’s decision follows the similarly motivated retirements of compatriot Joseba Beloki, a three-time podium finisher at the Tour de France, and Alexander Vinokourov, winner of the 2006 Vuelta.

Beloki, 34, had been without a team since being implicated, along with dozens of other cyclists, in the Operación Puerto doping investigation.

Vinokourov tested positive for homologous blood doping at this year’s Tour de France and was suspended for one year by Kazakhstan’s Cycling Federation. Earlier this month, Vinokourov announced plans to appeal the suspension, but also announced his retirement at the same press conference.

“I don't want this sport anymore,” said Vinokourov. “I'm slamming the door and I'm leaving.”

Born: February 1, 1974 in Béjar, Spain

Teams
1997-2000 - Kelme-Costa Blanca
2001-2003 - U.S. Postal Service
2004-2005 - Liberty Seguros-Würth

Grand Tour Performances (stage wins in parenthesis)

Vuelta a España
1997 - 5th; (Stage 12)
1998 - 6th; (Stage 19)
1999 - 3rd
2000 - 1st; (Stages 7 and 20)
2001 - 4th
2002 - 2nd; (Stages 6 and 15)
2003 - 1st; (Stage 20)
2004 - 1st; (Stage 12)
2005: - 1st; (Stages 6 and 15) - [results negated for doping]

Tour de France
2000 - 5th
2001 - 15th
2002 - 9th
2003 - 34th; (Stage 4 [TTT])
2004 - DNF
2005 - 45th

Giro d'Italia
1999 - 6th; (Stage 21)