David Parkin has revealed he sacked staff during his AFL coaching career over fears they were giving players illegal substances.

As the investigation into claims Essendon players were administered performance-enhancing drugs continues – with lawyers on Monday indicating players were unlikely to be interviewed by the Australian Sports Anti-Doping Authority until late next month – Parkin has suggested such drugs have been a long-time issue.

The four-time premiership coach began in the VFL/AFL at Hawthorn in 1977, spent time at Fitzroy and had two stints at Carlton, finishing his coaching career there in 2000.

”You could employ someone who for fame or fortune reasons becomes the rogue operator, if you like, within your organisation,” Parkin said. ”I have been down that path, where we have got rid of people who have serviced the needs of players that I did know about – we changed them because they were not doing the job the way we expected them to.”

Asked whether that meant a staff member had been trying to give illegal substances to players, Parkin said there was some evidence to suggest that might be so, ”and we weren’t prepared to take a risk that there might be somebody in the place that wasn’t operating all above board”.

Parkin spoke as a panellist on SBS Television’s Insight, which airs on Tuesday night.

Asked by journalist Jenny Brockie whether he had ”smelt a rat”, Parkin said it was a vague thing, but because of his position and responsibility, he couldn’t allow anything to develop.

Parkin, now president of the AFL Coaches’ Association, did not specify at which club or clubs he had sacked staff. He did not return calls from Fairfax Media on Monday.

Seated alongside former Essendon vice-captain Andrew Welsh and Port Adelaide sports scientist Darren Burgess, Parkin said sports scientists had become increasingly influential in clubs, and he felt the pressure on coaches to get an edge over competitors led to the temptation to bend the rules.

The original release of this article first appeared on the website of Hangzhou Night Net.