Cycling-Two in custody in Tour de France doping probe - Marseille prosecutor

PARIS, Sept 21 (Reuters) - Two people were in custody on Monday after an investigation was opened into suspected doping by the Arkea-Samsic team at this year's Tour de France, the Marseille prosecutor said on Monday.

Dominique Laurens said in a statement that the probe was targeting a "small part of the team" and that those in custody were part of the "close entourage of the main rider".

The prosecutor did not name the main rider. The leader of the Arkea-Samsic team is Colombian Nairo Quintana.

The probe targeted "the administration and prescription without medical justification of a substance or a method prohibited during a sporting event, and helping and encouraging the use of that substance or method," the statement added.

Searches led to "the discovery of many health products, including drugs, in their personal belongings and above all a method that can be qualified as doping," it said.

The Union Cycliste Internationale (UCI) told Reuters in a statement that it "welcomes and supports the action of all authorities involved in this operation."

The UCI said it will take "necessary measures once it has reviewed the elements obtained by the French judicial authorities.

"The probe being underway, UCI will not make further comments," it added. (Reporting by Marc Leras, Additional reporting by Julien Pretot, Writing by Dominique Vidalon; Editing by Ken Ferris)