Kevin Moses is the latest trainer staring at charges relating to cobalt use.

The Moses-trained Felix Bay returned an illegal level of the drug in a sample taken after he ran fifth at Hawkesbury on April 16.

The trainer has not yet been charged but will be called to an inquiry at a date to be decided.

Racing NSW chief steward Ray Murrihy his team had been to the trainer's Randwick stable and collected other samples.

"We have been to the stables and looked at the supplement and feeding program," Murrihy said.

"We have told Mr Moses and he has told his owners of the situation.

"The second sample from Felix Bay is being tested but the first returned a level above the threshold."

A national threshold of 200 micrograms per litre of urine came into force from January 1.

Sam Kavanagh is the subject of an ongoing inquiry into cobalt use in his Rosehill stable which he has admitted while Newcastle trainer Darren Smith has been disqualified for 15 years.

Victorian trainers Mark Kavanagh, Danny O'Brien and Lee and Shannon Hope have all been charged along with vet Tom Brennan from the Flemington Equine Centre.

Sam Kavanagh has told the Racing NSW inquiry that Brennan was the source of cobalt found in a post-race sample from Midsummer Sun after his Gosford Gold Cup win in January.