Sergio Henao has been withdrawn from racing by Team Sky after the Cycling Anti-Doping Foundation (CADF) requested more information regarding his biological passport values.
The Colombian rider was stood down by Team Sky for three months in 2014 following initial out-of-competition control tests taken at altitude in his homeland.
Team Sky revealed that Henao has not tested positive for a banned substance, but say he will not compete while the CADF look into his readings.
A Team Sky statement said: "Sergio has not failed a drug test and the CADF process is conducted confidentially. However, given that we have raised this issue in the past, we feel it is important to set out our latest position.
"We continue to support Sergio and remain confident in the independent scientific research which was undertaken. We will be helping Sergio make his case robustly over the coming period.
"He will also withdraw from racing until the issue is resolved given this contact from the CADF and the very obvious distraction to him. There is no obligation on us to do this but it is team policy if and when a formal process such as this begins.
"We do have to recognise the CADF process going forward so we hope people understand why we will be unable to give further commentary on it over the coming weeks.
"It is our hope that this can be looked at and resolved quickly by all the relevant authorities so Sergio can start racing again soon."
Henao said: "I am beyond disappointed. I have worked incredibly hard to get back to racing fitness after shattering my knee last year - but I know who I am, how hard I have worked and the sacrifices I have made to be where I am today.
"I am calm and confident that this will be resolved soon so I can get back to racing as soon as possible."