Trainer Jason Warren has been fined $17,500 for failing to report Baron Archer had undergone throat surgery before he raced at Echuca.

Stewards opened an inquiry into unusual betting activity surrounding Baron Archer after he finished third in a race at Echuca on March 8.

During the course of the inquiry they discovered Warren had not reported Baron Archer's throat surgery as required.

Warren, who pleaded guilty before the RAD Board on Friday, was fined $10,000 and another $7,500 for making a "false or misleading statement" during a raceday stewards' inquiry.

Stewards have said Warren is not under investigation regarding the betting.

Baron Archer opened at $2.70 then eased to $3.10 before being backed in to $2.80.

Investigations are continuing into a betting account in the name of the partner of disqualified jockey Danny Nikolic.

Baron Archer has been transferred from Warren to fellow Mornington trainer Wez Hunter.