Oisin Murphy’s return to action has been delayed after the rider failed to complete the medical requirements set out by the British Horseracing Authority.

The champion jockey was due to make his comeback with three rides at Lingfield on Friday following a three-month suspension.

He was banned after a drugs test at Chantilly in July showed metabolites of cocaine. He strenuously denied taking the drug and requested a B sample.

Upon receiving the results, France Galop held a hearing where the rider’s defence of environmental contamination from a sexual encounter and scientific hair test evidence was accepted.

However, early on Friday morning, Murphy posted on Twitter that he would be unable to take up his mounts at Lingfield and further rides at Chelmsford on Saturday due to an “administrative error”.

The BHA later clarified the situation in a statement, saying Murphy had not yet completed the necessary testing to return to competitive action.

The statement said: “Prior to returning to riding from a suspension of this nature, jockeys may be required to complete a course of testing, alongside other requirements, in order for the BHA’s chief medical adviser to confirm their safe return to race riding.

“On February 22 Mr Murphy contacted the BHA about his intended return to race riding. The BHA liaised with him and the PJA from this point onwards, including in regards to his testing requirements.

“On March 2 Mr Murphy was reminded of the requirements and that it is his responsibility to complete the necessary tests before a return to riding.

“As of March 12 Mr Murphy is only part way through his reinstatement testing, and he is therefore unable to ride at this point.

“Upon completion of the necessary processes satisfactorily, Mr Murphy will be able to return to riding.”

Murphy had earlier tweeted: “At 18.50 yesterday I was personally informed by the BHA due to an administrative error I will not be able to partner my rides at Lingfield today and Chelmsford on Saturday.

“I’m currently looking into this situation with the BHA and I plan to be back on the racetrack as soon as I possibly can.

“I apologise profusely to all the owners, trainers and supporters who I’m having to let down at such late notice. It’s 128 days since my last ride in the UK.”

Murphy later added: “Please note I can’t arrange testing personally. Only the BHA have the ability to do so. I’ve been available + completed all the tests thus far.”