NBA's Josh Giddey Subject of Police Inquiry Over Potential Underage Relationship

4:00 PM -- Thunder head coach Mark Daigneault was just asked about our report prior to Tuesday's matchup against the Minnesota Timberwolves ... and while he stated he will not comment on Josh Giddey's off-court situation, he reaffirmed Giddey will be available for the game.

Police are doing their due diligence on the recent troubling allegations surrounding Oklahoma City Thunder player Josh Giddey ... with officials opening an inquiry into whether he had an inappropriate relationship with a minor.

Law enforcement sources tell TMZ Sports ... Newport Beach PD is currently investigating the allegations involving Giddey made on social media over the past week ... to see if there is any validity to the claims and if any laws were broken.

As we previously reported, anonymous X accounts accused the 21-year-old Australian athlete of having an intimate relationship with a minor based in California ... and pictures and videos of Giddey with an alleged underage girl quickly spread online.

The NBA announced on Friday it was "looking into" the matter ... but so far, Giddey -- who has remained active with the Thunder following the allegations -- has declined to speak on it.

Of course, Giddey could be in trouble both criminally and professionally -- the age of consent in California is 18, while it is 16 in Oklahoma.

Giddey is currently averaging 12.1 points, 5.8 rebounds and 4.8 assists in 16 games this season.

We covered the story on the latest episode of The TMZ Podcast, available on all podcast platforms.