Both Baggaley, who finished runner-up in the men’s K1 and K2 500 metre events at Athens 2004, and his younger brother Dru pleaded guilty earlier this year to producing more than 18,000 pills of the party drug 2CB in 2013, and conspiring to make about 100 grams of methamphetamine, or ice.

The pair were jailed in 2009 for manufacturing and supplying large numbers of ecstasy tablets with Nathan serving two years of a four-year prison sentence before being released in 2011.

Sydney's District Court was told that while Dru was in prison between July and November 2013, he conspired with his brother - who was on parole at the time - and other people to manufacture the drugs.

The court heard the duo did not realise 2CB was illegal until soon after they started making it and did not end up selling the drugs.

In sentencing them to at least two years and three months in prison, Sydney District Court Judge Leonie Flannery said she thought the brothers had good prospects of rehabilitation, were unlikely to re-offend and had shown genuine remorse.

However, she added: "I consider that no penalty other than imprisonment is appropriate."

The Baggaley brothers' parents were in court on previous occasions, but did not attend to hear their son's sentences.

Nathan, voted Australian Institute of Sport Athlete of the Year in 2004, will be eligible for parole next November, and Dru could be released in July.

When Australian Federal Police arrested Nathan in November 2013, the former Olympian had helped set up drug laboratories in Currumbin Waters, Queensland and Tweed Heads, New South Wales.

He initially pleaded not guilty to all six charges he faced, including the importation of a commercial amount of drugs and the manufacture and supply of a "large quantity" of a prohibited drug.

In an interview in August 2013 to mark International Overdose Awareness Day, Nathan spoke out about his drug addiction but claimed he was now "clean".

"I've made some poor choices and paid the price," he said at the time. 

"I'm just happy to come home and try to get on with my life."