The president of cycling's governing body renewed his call for stiffer penalties for EPO use while insisting that cycling is the cleanest of sports.

International Cycling Union President Pat McQuaid told the French L'Equipe newspaper on Monday that he supports doubling the length of suspensions for first-time offenders who test positive for EPO from two years to four. He also said that Alberto Contador's (Team Saxo Bank-SunGard) doping case won't be resolved before the end of the year.

"Personally, I'm in favor of increasing the length of the suspension," said McQuaid, who backed the tougher punishments in a previous interview last month. "There should be a four-year ban for those who take EPO."

"We're going to propose that soon to the national federations and they will need to be on the same line as us."

The Spanish cycling federation is set to determine whether Contador is banned for two years after testing positive for clenbuterol during his victory in this year's Tour de France. Contador, a three-time Tour champion, blames contaminated meat for his positive test.

"At the end of August, along with WADA, we gave Contador the chance to explain himself," McQuaid said. "Twenty-four hours later, he told us this story of the contaminated meat. We asked experts to conduct a study to see if his version is credible. There won't be a decision before the end of the year."

Clenbuterol is a banned muscle-building and weight-loss steroid.

McQuaid also spoke about the possibility of handing reduced suspensions to riders caught using "lighter" substances.

"We should make a difference between light and heavy products," McQuaid said. "EPO is serious, that should be a four-year ban. Ventolin, for example, could be six or nine months."

In claiming that cycling is the cleanest of all sports, McQuaid said that most riders are not taking performance enhancing substances.

"Through our biological passport [program], we have noticed that the parameters were improving," McQuaid said. "Most of the riders are clean."