Four of Australia's top young footballers face possible fines and suspensions after an end-of-tournament night out in Cambodia.

Key points: Four top young Australian players face sanctions after a big night out in Cambodia

Four top young Australian players face sanctions after a big night out in Cambodia The players are members of the under-23 'Olyroos' team

The players are members of the under-23 'Olyroos' team The incident has only just come to light because it took months to investigate, due to its "complexity"

The ABC can reveal Football Federation Australia (FFA) will demand up-and-coming forward Lachlan Wales, young defender Nathaniel Atkinson and midfielders Brandon Wilson and Riley McGree explain their alleged behaviour, under a formal "show cause" process.

McGree, who has recently signed a three-year contract with Adelaide United, is captain of the national under-23 side.

The show-cause process — which provides the players with an opportunity to respond to the FFA's findings — follows an ABC investigation that uncovered a complaint lodged earlier this year to Sport Australia, the nation's rebranded sports commission, through a freedom of information enquiry.

The four players, members of Australia's under-23 'Olyroos' team, were in Phnom Penh at the end of March as they sought qualification for next year's Olympics.

The young players may be in breach of the FFA code of conduct, which requires players to:

At all times behave in a manner that promotes and upholds the highest standards of integrity, dignity and professionalism;

At all times behave in a manner that promotes and upholds the highest standards of integrity, dignity and professionalism; Comply with any team protocol and procedures, including in relation to alcohol, curfews and inappropriate relationships; and

Comply with any team protocol and procedures, including in relation to alcohol, curfews and inappropriate relationships; and Not act in a manner contrary to the best interests of the team.

The FFA has not confirmed the precise nature of the four players' behaviour, the findings of its investigation, or what prompted the Sport Australia complaint.

The night out came after Australia blew a two-goal lead to draw with South Korea in its final match of the tournament in March.

'Complex' investigation

The incident has only just come to light because it took months to investigate, due to its "complexity", the FFA told the ABC.

That inquiry delivered findings to the FFA board on October 3, which resulted in the show causes being issued.

"This follows an extensive, independently run investigation into a complaint received by the FFA," the FFA said in a statement.

"The investigation was initiated shortly after the complaint was received and, due to its complexity, took months to complete. The FFA board considered the findings of the investigation on October 3 and the board subsequently determined that the show-cause process should proceed."

Sport Australia is set up to receive complaints about Australian sports programs, but refers complaints made against a sport to the relevant sporting organisation.

When asked to clarify the status of the complaint, a spokesperson for Sport Australia stated the organisation, "has no public comment at this point".

Despite its name, the Olympic Stadium in Phnom Penh has never hosted an Olympic Games. ( Supplied: I G (via Flickr) )

Cambodian risks

The Smart Traveller website urges Australians in Cambodia to be wary of theft, sexual assault and "accepting invitations from strangers".

The FFA has offered the players counselling and is in contact with Professional Footballers Australia (PFA), the union representing footballers.

PFA chief executive John Didulica said his organisation, "is aware of an incident raised in relation to its members".

"As an independent investigation and subsequent disciplinary proceedings remain active, it would be entirely inappropriate and prejudicial to comment further on the matter," he said.

"Obviously, the players will continue to cooperate with the FFA throughout the process."

No consular assistance was provided to any player, according to a spokesperson for the Department of Foreign Affairs and Trade.

Previous breaches of the code of conduct by other players and coaches have prompted fines and suspensions.

The under-23 side returns to South-East Asia in January for the Asian championship. The top three teams at that tournament qualify for the Olympics.