Melbourne Cup-winning owner Luke Murrell has been fined $5000 over a social media post which questioned whether Chris Waller-trained runners were using team riding tactics.

The Australian Bloodstock director pleaded guilty to a charge of conduct prejudicial to the image and interests of racing levelled at him by Racing NSW stewards regarding a Facebook post on October 26 after a race at Canterbury.

Murrell posted an apology two days later saying he had no intention of accusing Waller of cheating and admitting he should not have questioned the integrity of stewards.

Through Australian Bloodstock, Murrell has syndicated and owned a number of horses including 2014 Melbourne Cup winner Protectionist.