Simmons, the Australian NBA superstar, accused Crown security of racially profiling him when stopping to check his group on entry to the casino on Monday night.

Simmons said he and his friends "felt personally singled out" by security, suggesting it was due to their skin colour.

"I find it so crazy ... wow, we got a long way to go," he said in a now-deleted Instagram video.

"I am very passionate about equality and I will always speak up even if it means having uncomfortable conversations," he Tweeted the next day.

Lemanis, speaking on Wednesday to unveil his 12-man squad for the World Cup, said he supported Simmons's right to speak up but wouldn't be drawn on whether his accusations were well placed.

"Ben's made his statement on that, and from my perspective, I support Ben and his right to to express how sees fit," he said.

"I wasn't there, so I'll just support Ben in his ability to express how he feels."

Crown denies discrimination, saying the 208-centimetre Melbourne-born Simmons was stopped by security as they believed he could be underage.

Lemanis overlooked Simmons, then 17, for the 2014 World Cup and was unable to select him for the 2019 event as the Philadelphia 76ers guard excused himself from national team duty on the basis of his NBA commitments.

The point guard signed a $241 million, five-year contract extension with the 76ers last month, believed to be the richest deal ever signed by an Australian athlete.

The Boomers stayed at Crown through their pre-World Cup training camp in Melbourne, and made the announcement at one of the complex's hotels despite the accusations.

Simmons's star status in the USA has resulted in the clash making headlines in America, embarrassing Crown.

His claim came a week after a damaging Channel Nine expose that showed alleged links to organised crime in China, and a deal with the Australian Government to give visas for big gamblers.

In a further awkwardness for the besieged casino and Basketball Australia, the World Cup squad was announced on a Crown property, ahead of the tournament in - of all places - China.

Australian Associated Press