Troubled former sports star Dennis Rodman is facing an investigation by U.S. officials over allegations he violated the country's sanctions against North Korea by giving birthday presents to Kim Jong-un.

The ex-basketball player jetted to the Asian nation earlier this month to visit his friend, dictator Jong-un, but checked into rehab after arriving back in the U.S. to address alcohol addiction.

Rodman is now facing further woes after it emerged officials at America's Treasury Department are reportedly investigating him over allegations he broke the country's laws which prohibit the importation of luxury goods into North Korea.

The probe relates to gifts the star bought for Jong-un's birthday, including whiskey, a fur coat, crystal glassware and a designer handbag for the North Korean leader's wife, according to TheDailyBeast.com.

Eugene Cottilli, spokesman for the U.S. Commerce Department's Bureau of Industry and Security, tells the website, "The Department is aware of the media allegations that Dennis Rodman may have transported luxury goods to North Korea.

"Our regulations require a licence for the export or re-export to North Korea of all U.S.-origin items except food and certain medicines. We do not comment on possible or pending investigations."