Brisbane Bullets training player Najeal Young has been deregistered by the NBL, effective immediately.
In a statement released on Thursday morning, the league said Young travelled to Adelaide with the Bullets squad for last weekend's preseason games against the 36ers.
"On his return to Brisbane earlier this week, he failed to undertake a COVID test and self-isolate as requested by the Queensland Government and the management of the Brisbane Bullets," the NBL statement read.
"All Bullets players and staff except Young have complied with the Government request to undergo testing and self-isolate for a period of 14 days. As a consequence of his action, Young, who is not a rostered Brisbane player, will be unable to take part in any NBL related activities including training."
The league said the incident had been referred to the Basketball Australia Integrity Unit for investigation.
The Bullets said they supported the NBL's decision.
"As a club we take the directions of the Government and Chief Health Officer very seriously and Najeal's failure to do so was unacceptable and we fully support the NBL's action," Brisbane CEO Peter McLennan said.
"The health and safety of our players, coaches, staff and the broader community has always been our priority.
"Our players and staff affected will continue to self-isolate for a period of 14 days as directed. Players will complete a training program from home as they prepare for the 2020-21 NBL season due to commence in mid-January."