French police are investigating the Cofidis racing team.
Former Cofidis rider Marek Rutkiewicz and team assistant Boguslaw Madejak were arrested after banned substances were found in their possession.
"I would never have believed that this could happen," said Cofidis general manager Alain Bondue. "I trusted all my employees, it's a shock."
Police searched the Cofidis headquarters in Paris but failed to find anything illegal.
Rutkiewicz and Madejak, who has worked with the team since 1997 as a nutritionalist and phsyiotherapist, are suspected of supplying tour riders with banned substances.
Cofidis team doctor Dr Jean-Jacques Menuet, who also looks after the French athletics sprint team, was interviewed by police.
Britain's time-trial champion David Millar is one of the members of the Cofidis team along with world road champion Igor Astarloa and sprint specialist Laurent Gane.
But police stressed that Millar and his team-mates are not suspected of having any involvement.
Rutkiewicz rode for Cofidis for two years before joining French team RAGT Semences-MG Rover.
The team, formerly known as Jean Delatour, has suspended the Polish rider and will take further action if he is found guilty of a doping offence.
"If Marek Rutkiewicz is shown to be guilty after a police inquiry, he will be dismissed definitively," said the team in a statement. "These are the terms of the law."