An Australian medallist at the Invictus Games has quit the team following revelations he is facing drug and weapon charges, after he was allegedly found with a stash of steroids, cocaine and peptides last month.

Afghanistan veteran Tyrone Ian Gawthorne — who gained publicity for his brush with Games founder Prince Harry while training for the event last year — was arrested by Queensland police in Cairns on September 17.

It is alleged Mr Gawthorne was found in his car with the anabolic steroid fluoxymesterone, the peptide melanotan, over two grams of cocaine and a weapon not properly secured.

The 2017 Invictus Games silver medallist won another silver medal last night in powerlifting.

However, in a statement in response to ABC queries Mr Gawthorne said he had not told team officials about his arrest, and would no longer compete at the games.

"I cannot express how sorry I am for not disclosing to the team that I had been arrested," he said.

"I have let down my family and friends and my teammates, and my actions are not in keeping with the spirit of the Games.

Prince Harry with Invictus Games athlete Tyrone Gawthorne, last year. ( Facebook: Tyrone Gawthorne )

"I would like to sincerely apologise to everyone who has been affected by my actions."

Mr Gawthorne insisted that "I have not taken any substance that would unfairly enhance my sporting performance at the Games".

He faces two counts of possessing dangerous drugs, as well as restricted drugs without medical endorsement.

The latter allegedly included letrozole and anasprozole, which can be used to treat the unwelcome side effects of steroid use.

He is due to front Cairns Magistrates Court again in December, including on charges of failing to safely secure a weapon in his car and flouting a police order to unlock an electronic device.

Gawthorne won a silver medal in powerlifting at the 2017 Invictus Games, and again in 2018. ( Facebook: Tyrone Gawthorne )

Mr Gawthorne has featured in publicity material for the games but his profile has been removed from the Australian Defence Force website.

The former army rifleman — who owns a hotel, a gym and sports supplements stores called Body Beyond Belief in north Queensland — was also featured as an entrepreneur in The Australian newspaper's The Deal magazine last month.

He was arrested five days earlier on a street in Mooroobool, in Cairns' west, and held in the watchhouse overnight before a magistrate granted him bail.

He told The Australian last month he was medically discharged from the Army in 2011 with physical injury and post-traumatic stress disorder after two tours of Afghanistan and three of East Timor.

Australian team management said it was aware of allegations made against a 2018 Australian Invictus Games team member.

"All members of the 2018 Australian Invictus Games team are bound by the team code of conduct. This code reflects the standards and values of the Invictus Games," it said.

"Appropriate action will be taken in the event anyone is found to have breached the team code of conduct.

"As this is an ongoing legal matter, we are not able to make any further comment."