An Olympic shooting gold medallist has lost his chance to compete in the 2024 Paris Olympics after a New South Wales tribunal upheld a decision to refuse his gun licence application.

Michael Diamond, 51, had his Category A firearms licence revoked in 2018 after he was found guilty of firearms and drink driving charges in Port Stephens in 2017.

He had challenged the decision but the appeal was upheld in January last year.

In September, he sought an administrative review of a decision to refuse a new application for a gun licence.

That decision has been upheld by the NSW Civil and Administrative Tribunal, meaning he will not be able to take part in the upcoming national Olympic qualifiers.

The 51-year-old had been a successful competitive sporting shooter since a young age and won two gold medals in the sport at the 1996 and 2000 Olympics.

'Needed licence' for upcoming Olympic qualifiers

Diamond had told the tribunal he needed a firearms licence before January 16, 2024 to "compete at the Australian National Titles, the first selection competition for the [Paris] Olympic Games".

Diamond argued he could be trusted given the work he had put in to improve himself since the ban was imposed.

The judgement handed down on January 5 stated Diamond had undertaken therapy, a road intervention program and firearm safety training.

Fellow Olympian Russel Mark OAM gave a character reference and said he "could not speak more highly of Michael as a competitor".

"He has only ever conducted himself with utmost respect and dignity," he said.

According to the judgement, Diamond said he had lost more than $1 million in sponsorship and related income due to losing his licence.

The NSW Police Force argued the programs and mentoring undertaken by Diamond did not amount to "significant steps in demonstrating reformed behaviour" due to the serious nature of his offending.

The tribunal ultimately found Diamond had not taken enough steps to improve his behaviour and that granting a firearms licence would not be in the public interest.

"Even if I were to accept genuine remorse and commitment to reformed behaviour, the tribunal cannot ignore the applicant's history," the judgement stated.

"The weight of that history is such that it cannot be overcome by a recent period of mentoring, counselling and training.