Daniel Edmund Duggan was arrested in Australia in October 2022 at the request of the US government, which accuses him of breaking arms control laws.

It alleges he illegally trained Chinese military pilots between 2010 and 2012, after he left the Marines.

Duggan has denied the charges.

Australia's Attorney-General Mark Dreyfus decided in December that Duggan would be extradited to the United States "to face prosecution for the offences of which he is accused".

Duggan's lawyers launched a legal appeal late Monday in Australia's Federal Court to appeal his decision, his wife Saffrine said in a statement.

"We have been forced to resort to court action because the government has not been transparent about this case, despite Dan being locked up in maximum security prison for the past 26 months with no Australian charges," she said.

"Dan is exercising his rights as an Australian citizen to due process under Australian law. We are an Australian family, and we deserve a fair go."

Duggan, a father of six, first moved to Australia in 2002 after leaving the Marines, gaining citizenship and working in an adventure flight company called Top Gun Tasmania.