Milwaukee Bucks basketballer Andrew Bogut could face a hefty fine after making an obscene gesture at home fans when being ejected during the Bucks' 108-93 loss to Toronto on Tuesday (AEDT).

The young Australian, who was taken by the Bucks as the NBA's No.1 pick in the 2005 draft, was clearly frustrated when sent for an early shower after committing a flagrant foul on Toronto's Chris Bosh.

As Bogut left the court with 49 seconds remaining, television cameras caught the centre gesturing obscenely to the crowd.

In a club statement, Bogut apologised to the fans, with the centre saying they certainly did not deserve such treatment.

"Our fans have been very supportive of me since I came to Milwaukee," said Bogut.

"I got caught up in the heat of the moment and let my emotions get the best of me," he added.

NBL officials have not yet fined Bogut for his actions, but he could face a US$25,000 penalty after Atlanta Hawks forward Josh Smith was fined that amount for a similar offence.