Cape Town - Top South African mountain biker Max Knox has been found guilty of doping and received a ban for four years from the South African Institute for Drug-Free Sport (SAIDS).

SAIDS made the announcement on Tuesday that Knox was charged for suspicious variations in his Athlete Biological Passport, that indicated doping and could not give a satisfactory explanation to the panel of international experts appointed.

The former SA Marathon MTB champion represented the country several times at the World Cross Country Championships. According to the ruling, he will be stripped of all his titles from 16 June 2015, and will also have to return all prizes, money and medals since that date.

Knox’s ABP monitored from February 2013 to June 2017 included irregularities of an artificially increased haemoglobin concentration, bone marrow stimulation, followed by bone marrow suppression.

The ABP was reviewed in conjunction with the cyclist’s competition schedules, race results and intelligence supplied to SAIDS. However, Knox’s explanations and supporting documents were rejected by the panel, as they don’t provide explanations for the irregularities.

He further appealed against the initial decision, but failed to file any documentation within the prescribed filing period. Knox was one of the three mountain bikers given doping bans in the past 18 months, as a result of a year-long investigation and tip-offs.

SAIDS CEO Khalid Galant said that the convictions came from the first phase of the investigation undertaken in collaboration with the Hawks.

‘The investigation will continue to look at athletes, doctors and trainers whether they have a role in the doping supply network’, said Galant.

SAIDS announced early this year that Shan Wilson who was tested 25 March 2014, was one of the three bikers found guilty of doping offences.

He was banned for six years after being found guilty of doping on five counts, which included the presence, attempted trafficking or trafficking of a prohibited substance and complicity.

A female biker tested in March this year was banned for two years after an adverse analytical finding for Erythropoietin.

"The investigation was triggered by whistleblowers and we are very grateful to their efforts to keep sports clean," said Galant.

"We take tip-offs about any sporting discipline or individuals seriously and encourage people with good information to come forward. Any information remains strictly confidential and can be submitted via our website on an anonymous basis."

-Team SA