Cofidis, a professional cycling team, said it was aware that its cyclist Remy di Gregorio "had allegedly attempted to resort to the use of doping substances to improve his performance" and therefore was suspending him as a precaution.
Police raided the hotel where some members of the Cofidis team were staying in Bourg-en-Bresse, in eastern France, Tuesday morning, he said.
Two other people were detained in Di Gregorio's hometown of Marseille in connection with the ongoing investigation, the police official said.
Cofidis said in a statement that it had "very little information" at present, but that the suspicions weighing against Di Gregorio "lead us to apply the current sanctions in a strict and immediate manner in our team, concerning the violation of ethical rules.
"Remy di Gregorio is therefore suspended, from now, as a precaution, as we wait for more ample information concerning the reality of the crimes of which he is accused. If these crimes are established, he will be dismissed immediately as per the terms of his contract and the ethical policy of the team."
The investigating judge in the case is Annaick Le Goff, who is a judge for the health division, the national police official said. Tuesday's arrest was made in a joint operation with the division of public health of the Marseille Gendarmerie, he added.
Di Gregorio is currently ranked 35 out of 178 competitors, according to the Tour de France website, trailing British cyclist Bradley Wiggins, who holds the lead by just over 18 minutes ahead of Wednesday's resumption of the competition.
Tuesday was the first rest day for the riders taking part in the world's best-known cycling race, which began June 30.
In the course of the race, which consists of a short time trial prologue followed by 20 longer stages, the cyclists will cover 3,497 kilometers (2,173 miles), including grueling mountain climbs, before they cross the finish line in Paris July 22.
Di Gregorio joined the Cofidis team this year, having previously competed with the Astana professional cycling team, which is backed by Kazakhstan. He came in 78th in the Tour de France in 2010 and 59th in 2008, and has won three stages in the eight years he's been competing in the race.
Spanish cyclist Alberto Contador was part of the Astana team when he won the Tour de France in 2010. He was later stripped of the title and banned from competing for two years by the Court of Arbitration for Sport, after failing a drug test.
The issue of alleged doping in professional cycling was thrust into the spotlight last month, when the U.S. Anti-Doping Agency accused U.S. cyclist Lance Armstrong of using performance-enhancing drugs.
Armstrong, who denies the allegations, faces a lifetime ban and could be stripped of his seven Tour de France victories if found guilty by the USADA. He won the Tour each year from 1999 to 2005.