British cyclist Simon Yates has failed an in-competition drugs test — with his team blaming an "administrative error" over an asthma inhaler.
Orica-GreenEdge said they took "full responsibility for the mistake" and there was "no wrongdoing" by Yates.
He tested positive for banned substance terbutaline and a team doctor failed to apply for a therapeutic use exemption (TUE), the Australian team said.
Orica will "fully support" the 23-year-old during the investigation.
"This is solely based on a human error that the doctor in question has taken full responsibility for," Orica added.
Yates, a former points race world champion, is regarded as one of Britain's brightest prospects on the road, along with his twin brother Adam.
He is a strong contender to make the TeamGB road race team for the Rio 2016 Olympics this summer.
The sport's governing body, the UCI, notified British Cycling of a "potential anti-doping rule violation" based on an "in-competition sample" at the Paris-Nice race in March.
Proceedings will be managed by the UCI independently, according to a spokesman for British Cycling.
"It would be inappropriate to comment further until the process has been completed," the spokesman added.
Yates, a climber with Orica, achieved a top-10 finish on the Mur de Huy stage of last year's Tour de France, and was seventh in last month's Paris-Nice race.
The team are "concerned by the leak" of Yates' failed test and are now submitting all evidence to the UCI.
"The substance was given in an ongoing treatment of Simon Yates' documented asthma problems," Orica said.
"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."
News of the failed test comes in a bad week for British Cycling, with technical director Shane Sutton resigning on Wednesday amid claims of sexism and discrimination.
British Cycling is investigating claims the 58-year-old Australian used derogatory words to describe Para-cyclists, while an independent review will also look into rider Jess Varnish's accusations that Sutton made sexist comments and told her to "go and have a baby".
Sutton "rejects the specific claims" but said the allegations against him had "become a distraction" to British athletes before this summer's Rio Olympics.
A third inquiry was ordered on Thursday, with separate claims that official British Cycling kit was available to buy online.
British Cycling denied any equipment provided by UK Sport had been given away or sold on for profit, but said other unwanted kit from commercial partners is sold or given away.
Sutton was also asked to attend a meeting on Tuesday to discuss the kit allegations, revealed in the Daily Mail.
UK Sport, which helps fund Britain's Olympians and Paralympians, ordered the investigation to "protect our investment in all sports on the world-class programme".
BBC sports editor Dan Roan
"This is now in danger of turning into the worst week in the history of British cycling. The sport's showpiece UK event — the Tour de Yorkshire — starts on Friday with more than a million people expected to watch the action.
"But it risks being overshadowed by a mounting crisis at the embattled national governing body. All this just three months out from the Olympics.
"The timing could not be worse for British Cycling, so often heralded in recent years for its record in both performance and participation."