Orica-GreenEdge cyclist Simon Yates has returned a positive result for a controlled substance, as confirmed by his team on Thursday.
British rider Yates tested positive for Terbutaline at Paris-Nice in March following a test conducted after stage six of the event, with Orica-GreenEdge notified of an "adverse analytical finding" last Friday.
Orica-GreenEdge blamed an administrative error over an asthma inhaler used by Yates, insisting there was "no wrongdoing" by the 23-year-old.
The news adds to an already tumultuous week for British Cycling, after director Shane Sutton resigned following allegations of discrimination.
And the confirmation comes just hours after British Cycling announced it had been notified of a possible anti-doping rule violation by one of its riders.
"On April 22, the team was notified that Simon Yates has an adverse analytical finding from a test conducted at Paris-Nice, stage 6 on March 12, 2016," the statement said.
"The positive result is for the substance Terbutaline.
"The substance was given to Simon Yates in the form an asthma inhaler and accordingly, this was noted by the team doctor on the Doping Control Form, signed at the time of the test.
"The substance was given in an ongoing treatment of Simon Yates' documented asthma problems. However, in this case the team doctor made an administrative error by failing to apply for the TUE required for the use of this treatment.
"The use of Terbutaline without a current TUE is the reason it has been flagged as an adverse analytical finding. This is solely based on a human error that the doctor in question has taken full responsibility for."
The statement went on to say that the result was not Yates' fault and that the team, "takes full responsibility for this mistake and wishes to underline their support for Simon during this process.
"The team is concerned by the leak of this information and has no further comments until there has been a full evaluation made of the documentation, statements and evidence that the team and Simon Yates are now submitting to the UCI in order to clarify everything."