The Chris Waller-trained Betcha Thinking has been confirmed as the horse to return a positive swab to methamphetamine.

Waller was told a few weeks ago, a first sample showed the presence of the drug which has the street name ice.

On Monday, Racing NSW stewards said testing on the second, or B, sample confirmed the presence of the drug in a post-race test taken after Betcha Thinking ran second at Canterbury on October 5.

Recent cases involving Victorian trainer Matt Laurie and Scone trainer Luke Griffiths were determined to have come from human-to-horse contact while a case involving John McNair was suspected of being a deliberate act by someone outside the stable.

Waller, who employs a large team of people has tested his staff with no positive results to the drug.

The trainer will attend an inquiry on Friday morning.