“On the basis of additional information... we have identified the relevant samples and carried out the first analyses,” a spokesperson for the Cycling Anti-Doping Foundation (CADF) was quoted as saying by Het Nieuwsblad.
The newspaper reported that the re-testing operation is part of an inquiry into the Aderlass doping affair, which first came to light when Austrian police raided the Nordic skiing world championships in 2019.
Eight professional riders have since been implicated in that scandal.
Last November, the International Cycling Union (UCI) said it had asked the CADF to analyze samples from the 2016 and 2017 seasons amid the Aderlass affair.
UCI officials were not immediately reachable by Reuters for comment.
According to the Het Nieuwsblad report, the doping labs of Seibersdorf in Austria and Cologne in Germany are in charge of the analysis.