Chinese basketball sees first doping case

"We should learn from this lesson. We should conduct more tests and  improve the regulations. We have zero tolerance towards doping," the CBA said in Monday's statement.

For Williams, the punishment means he will have to sit out the rest of the season and his team is free to replace him with another foreign player.

Williams, 26, apologized right after the CBA's announcement.

"To all the CBA fans, Shanxi fans, sponsors, as well as my coaches and players, I sincerely apologize. I have let a lot of people down and I regret it more then anything. I understand everyone's disappointment and I will do everything to improve and grow from this," said Williams who had the best three-double record in 2010 season.

Then he said he used marijuana to relieve stomachache, according to the report of Beijing Daily.

Williams had played for the San Antonio Spurs and Los Angeles Clippers before he moved to China to join Zhejiang in 2010. He was transferred to Shanxi in 2011 and averaged 32.1 points, 5.6 rebounds and 3.7 assists last season.