A North Queensland trainer has become the latest to be banned for use of cobalt, with Glen Bakergiven a two-year disqualification over a positive test for his horse French Lesson when it won at Doomben in January.

Baker becomes the fourth Australian trainer, after NSW’s Darren Smith (15-year ban) and Sam Kavanagh (banned, awaiting sentence) and Western Australia’s Sharon Taylor (18 months) to be banned for use of the substance.

Investigations are ongoing in several states and a decision on whether charges will be laid against four Victorian stables - Peter Moody, Mark Kavanagh, Danny O’Brien and Lee and Shannon Hope - is expected in the coming weeks.

Baker had pleaded not guilty despite separate analysis of the samples recording French Lesson’s cobalt levels at 790ug/L and 846ug/L, well above the 200ug/L) adopted nationally from January 1.

He claimed that the horse’s feeding regime had contributed to the elevated level, but this was rejected.

Baker’s disqualification will take effect from Monday June 8, 2015 pending any appeal.