One of key players in the battle against the use of cobalt in Australian racing is leaving to take up a position in Hong Kong.

Racing Victoria's head of equine welfare and veterinary services Dr Brian Stewart will take up a position with the Hong Kong Jockey Club.

He has been appointed as the head of Veterinary Regulation and Biosecurity to manage the movement of horses between Hong Kong and the HKJC's Conghua Training Centre in China.

RV chief executive Bernard Saundry said it was disappointing to lose someone of Stewart's international standing and experience.

"I wish to thank Brian for his commitment to furthering the welfare of the thoroughbred, strengthening drug controls and improving veterinary regulation which has been truly valued by the organisation," Saundry said.

Stewart began his role with RV in 2011 and will leave his post after the Melbourne Cup carnival.