The public prosecutor's office of Marseille opened a preliminary investigation into possible doping use in the Tour de France on Monday.
According to various media, the investigation focuses on Arkéa-Samsic, the team of leader Nairo Quintana.
A spokesperson for the public prosecutor's office has confirmed the preliminary investigation to AFP news agency.
It speaks of "the discovery of many health products, including drugs and substances that can be seen as doping".
On Wednesday there was already a house search at the French hotel where Arkéa-Samsic was staying.
Foreman Emmanuel Hubert confirmed this to
, but did not want to say anything about the reason.
Several French media report that leader Quintana is one of the riders whose room was searched.
His teammates Dayer Quintana and Winner Anacona would also be in trouble.
Thirty-year-old Quintana is number two on the Tour de France in 2013 and 2015. The Giro d'Italia winner of 2014 and Vuelta a España winner of 2016 could not compete with the very best during the last Tour and finished seventeenth.
The 107th edition of the Tour, which ended in Paris on Sunday, was won by Tadej Pogacar.
The Slovenian from UAE Team Emirates drove his fellow countryman Primoz Roglic from Jumbo-Visma out of the yellow jersey in the penultimate stage.
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