Josh Giddey will not face charges after police in California dropped an investigation into the Australian NBA star’s alleged relationship with a minor.

Giddey was the subject of an NBA and police probe following an allegation in November that the Boomers guard had been in a relationship with an underage girl.

California’s Newport Beach Police Department (NBPD) on Thursday confirmed the case was closed.

“Our detectives have reviewed all of the available information regarding allegations circulating on social media and were unable to corroborate any criminal activity related to Mr Giddey,” NBPD crime prevention specialist Heather Rangel told AAP.

The NBA is yet to comment on the matter, commissioner Adam Silver saying in December the league wouldn’t take action until the police investigation concluded.

In a since-deleted post, an anonymous social media user said a girl seen with Giddey in videos and photographs was a high school junior at the time.

The social media account has since been deactivated.

Giddey declined to comment on the accusations in November and has continued to play since for Oklahoma City, finding form as the Thunder (27-13) moved to second in the NBA’s western conference.

The No.6 pick in the 2021 NBA Draft, Giddey is averaging 11.8 points, 6.1 rebounds and 4.6 assists in 39 games for Oklahoma City this season.

The 21-year-old, who at 19 became the youngest NBA player to record a triple-double, looms as a key performer for the Boomers at the Paris Olympics, which begin in July.

Boomers coach Brian Goorjian travelled to the USA in December to meet with prospective NBA-based Olympians and reached out to Giddey before the trip.

“He is a young man and you are part of his development. We have a responsibility, and I do, to develop him as a human being,” Goorjian told AAP in November.

“When you are in trouble or there are things not going your way, or you have got some problems as has been the case with other players … you are just open and let him know you are there for him.”