Biarritz say former Wales scrum-half Rhys Webb has been provisionally suspended by French authorities following a positive drugs test for growth hormone.
Webb was tested by the French Anti-Doping Agency (AFLD) during a training session with Biarritz in July.
An investigation has been launched with a potential ban if found guilty.
Webb retired from international rugby before the 2023 World Cup and joined the second tier French side.
It is understood there was a slight anomaly in Webb's hormone levels and the player himself is protesting his innocence and has sought legal advice.
He scored a try on his Biarritz debut against Colomiers but was not involved this weekend.
"Rhys came to me on Monday and he showed me the letter from the French Anti-Doping Agency," said Biarritz president Jean-Baptiste Aldigé.
"The letter said Rhys was positive for some products. He has to attend a meeting on Monday with them. It's not a court hearing. At this stage, he is not guilty.
"The meeting is just to explain the results. As club president, I am waiting for the result. The result was last Monday. The test was on July 14.
"Rhys was the one to receive the test results. As a club, we are not involved. After the meeting on Monday, the decision will be made whether to go to court or not.
"As soon as you get a strange result, you are provisionally suspended as a player."