Di Gregorio, 26, was arrested following a police raid at his team’s hotel in Bourg-en-Bresse, several miles outside Macon in eastern France where the race will resume for the 10th stage on Wednesday.
A team statement said: “We have just learned that one of our riders, competing at the Tour de France, may have attempted to resort to doping substances to improve his performance.
“At the current time, we have very little information about the facts of the case.
“However the suspicion on the rider concerned, Remy di Gregorio, leaves us with no choice but to hand down the strictest possible sanctions.
“Remy di Gregorio is therefore immediately suspended, provisionally, while we await more ample information on the case.
“If the suspicions are confirmed, he will be sacked on the spot — in accordance with the stipulations in his contract and in line with the ethical policy of the team.”
It is not the first time one or several riders from Cofidis have been embroiled in a doping affair.
Several riders including Briton David Millar and Frenchman Phillipe Gaumont were implicated in a damaging doping affair in 2004, leading to radical changes at management level.
Three years later, under pressure from organisers, the team voluntarily left the 2007 Tour when Italian rider, Cristian Moreni, tested positive for the banned blood booster EPO (erythropoietin).
In 2007, current Tour de France leader Bradley Wiggins, now of Team Sky, was part of the Cofidis team that went home after the 16th stage.
Tour de France officials have yet to comment on the case.
But Cofidis hope to avoid the same fate as five years ago.
The statement added: “We believe however that this isolated case should not place any doubt on the team’s continued participation in the Tour de France, or penalise those who have nothing to blame themselves for.
“The team will therefore line up for the race tomorrow morning.”
Cofidis stressed they had the strictest rules concerning ethics in the team.
“In recent years we have put in place an exemplary anti-doping programme that goes well beyond what is imposed by the international anti-doping authorities.
“We see that in spite of these measures we are powerless in the face of individuals with no scrupules who tarnish the image of the sponsor and sully the reputation of all the riders in the team.
“Consequently, all existing measures will not only be maintained but reinforced in the coming days.
“We want to make it loud and clear: anyone who cheats has no place in the Cofidis team.”
Di Gregorio was arrested earlier Tuesday as part of an investigation into the organised trafficking of doping substances, Marseille magistrate Jacques Dallest told AFP.
He was taken into police custody in Bourg-en-Bresse and was brought to Marseille for further questioning by investigating magistrate Annaick Le Goff, Dallest said.
Two other unidentified men, who are suspected of “having dealings” with Di Gregorio, were also taken into police custody.
Le Goff said earlier that the investigation had been “opened last year”.
Prior to joining Cofidis for the 2012 season Di Gregorio raced with the Astana team, which is also racing the Tour de France.
Astana were also thrown off the race in 2007, after then leader Alexandre Vinokourov of Kazakhstan tested positive for blood doping.
Di Gregorio turned professional in 2005. His most notable success was a stage in the Paris-Nice in March 2011.