Brisbane jockey Glen Colless has lost an appeal against a suspension but has had his ban reduced from 17 days to 12.

Colless was outed after he was found guilty of causing interference in the concluding stages of the Group One BTC Cup on May 14 which he won on Malaguerra.

Stewards found Colless had allowed Malaguerra to shift in near the line causing tightening to Two Blue, Delectation and eventually Artlee who lost his rider Michael Cahill.

Colless, who rode through the winter carnival on a stay of proceedings, strongly defended the charge at Tuesday's Racing Disciplinary Board hearing in Brisbane, arguing Jason Collett on Delectation had gone for a run inside Two Blue and outside Artlee at the 100m mark.

"He said Two Blue had shifted in which caused Delectation to be checked and move onto Artlee," Colless said.

"I had no bearing on Two Blue moving in. Paul King on Two Blue kept riding because he didn't realise there were two horses inside him, The accident started before I even got to it.

"There shouldn't have been three horses inside me, there was room for two and as it happened behind me I wasn't to know."

Chief steward on the day, Martin Knibbs, said the panel had found Colless' mount Malaguerra had shifted in from four horses off the fence at the 150m to one off at the finish line.

"It was enough to sustain the charge of interference," he said.

RDB chairman Brock Miller said the panel had viewed the race film and also considered the evidence at length.

"Our view is slightly different to Mr Colless. We find his mount did move in over the final stages and therefore the charge was sustained," he said.

Miller said the panel reduced the suspension because of Colless' good record.