• What is clenbuterol?
• Who are Lachie Keeffe and Josh Thomas?

NATHAN Buckley has spoken of the devastation both he and Collingwood felt when hearing of the positive drugs tests returned by Lachlan Keeffe and Josh Thomas.

Speaking on Fox Footy's AFL360, Buckley described the pair as "cleanskins", but admitted the Magpies were still relatively in the dark as to how they tested positive to the banned substance clenbuterol.

Keeffe and Thomas were informed of the results on Friday, and Buckley said the club was advised against speaking to them over the weekend as the players investigated their own legal options.

But the Collingwood coach was distraught with the news.

"We were devastated to find that out as a fact," Buckley said.

"They're very decent, upstanding young men.

"If you asked me a couple that wouldn't have tested positive to anything, they'd be right up there these two boys.

"They're cleanskins, and yet they've returned a positive sample to a performance-enhancing drug."

Keeffe and Thomas tested positive on February 10, two days after the team returned from a New Zealand training camp.

AFL may need to look at drugs policies: McLachlan

Buckley said Keeffe and Thomas were roommates on the trip and are best mates.

"In many ways, they've been joined at the hip their whole career," he said.

Their coach added there was no logical reason why they would take a banned substance such as clenbuterol, which helps build muscle and burn fat.

He noted Keeffe and Thomas had overcome serious injury problems in the past few years.

"Both of these boys have had reasons throughout their career where they might want to go to it (taking banned substances) ... but they've had their opportunities and they haven't," Buckley said.

"They've just worked hard and plugged away and they're right in the sweet spot of their careers.

Buckley said Collingwood had thoroughly investigated its own nutritional program and was confident it was clean, adding that it was frustrating the club did not know more about the positive tests at this stage.

"We'll speak to both players in the next 24 to 48 hours to understand what's going on because the club's in the dark relatively," he said.

"We got independent legal advice that said "we can't talk to you right now".

"We haven't been able to speak to the players regarding specifics and facts and that's something we need to get to from their perspective so that we understand where we stand as a football club."

Buckley said his primary concern at the moment was their stress levels and mental state.

"We're devastated for them, they're devastated and we just need to get to the bottom of this to work out how this has come about."

Clenbuterol is the banned substance that cost Spanish cycling ace Alberto Contador his 2010 Tour de France title because of a positive test.

Australian cycling star Michael Rogers also tested positive to clenbuterol, but was cleared on appeal.

Contador and Rogers had the same defence - that they ate contaminated meat.

Meanwhile, the AFL Players’ Association has refuted reports it threatened federal court action over the release of the players' names.

"The PA did however ask that neither the AFL nor the club release the names of the players involved until we had spoken to the players and had their approval to do so," CEO Paul Marsh said.

"This occurred around lunch time today."