Dale Steyn has been asked to explain an abnormal drugs test finding during the Indian Premier League, Cricket South Africa (CSA) have confirmed.
The results of the test - which had Steyn showing higher than normal amounts of morphine - are believed to have been caused by painkillers taken by the Proteas paceman to relieve chronic migraines.
Steyn, who was playing for the Bangalore Royal Challengers at the time of the test, has responded to the IPL's doping authorities and CSA are confident his explanation will prove satisfactory.
"During the IPL's normal doping tests they found an abnormal analytical finding in one of Dale's tests, said South Africa team doctor Mohammad Moosajee.
"Since last summer Dale has been laid low by chronic migraines and has been taking a codeine painkiller called Myprodol. In the body codeine converts into morphine and the normal level of morphine is one microgram (per ml), Dale was at around 1.1 to 1.3.
"Because he was slightly above the level, they wanted to know why. A letter has been written to the IPL and we are awaiting the reply.
"But this is an adverse analytical finding and that is totally different from a doping violation."
Moosajee also insisted he was fully confident it would not be long before Steyn, who kept a written log of his medication intake, was fully cleared.
"As soon as the IPL come back to us and tell us they accept the explanation it will not be a problem, this happens all the time with players," he said.
"Until the finality comes from the IPL we won't know but we are confident right now that this is not a big issue."
Myprodol is not a banned substance and Moosajee believes there may have been a misunderstanding surrounding its use due to a branding issue.
Players are allowed to apply for Therapeutic Use Exemption for certain products and Moosajee added: "Dale wrote down what he had been taking for his migraines but he and the team physios are obviously South Africa based.
"Myprodol may not be called Myprodol where he was playing so they wanted to know why the levels were high."