Just as cycling's head was saying a clean world road championships was key to repairing the sport's tarnished image, three South American riders were suspended from competing on Wednesday.

Pre-championship testing revealed excessive hematocrit levels in the blood of Argentines Martin Garrido and Matias Medici and Brazil's Magno Nazaret. The levels made it dangerous for the trio to compete this week, and they were not allowed to race for two weeks. The ban didn't mean they were caught doping.

In all, 18 riders were tested from Brazil, Argentina, Australia, the United States, and Switzerland.

Cycling has been hit hard by doping scandals this year, none bigger than Tour de France winner Floyd Landis' positive test for elevated testosterone.

Cycling was desperate to clean up its reputation, said International Cycling Union president Pat McQuaid.

"We have been working on a daily basis to solve the problems. That is now our main goal," he said.

Italy's Ivan Basso and Germany's Jan Ullrich were among riders excluded at the start of the Tour de France after their names turned up on a list compiled by Spanish doping investigators.

Five people _ including Spanish doctor Eufemiano Fuentes _ were arrested and charged when police seized drugs and frozen blood at a Madrid clinic in May. Ullrich, who won the 1997 Tour de France, was fired by his T-Mobile team.

"This week will be extremely important to our sport," McQuaid said. "It hasn't been a good year so far since the doping issues arose in July."

McQuaid said it was of the "highest importance" to further improve doping control measures, noting that Team CSC had appointed an anti-doping expert and that the T-Mobile team had sharpened its anti-doping regime.

"I am grateful to see that many teams and national federations are already taking steps forward in this respect," he said.

McQuaid told The Associated Press after the news conference UCI was trying to gather a team of psychologists who would work with the riders. He declined to be more specific.