An alleged Hong Kong triad boss known as "Shanghai Boy" was arrested Wednesday on suspicion of laundering more than 100 million Hong Kong dollars ($12.8 million), police said.

Businessman Kwok Wing-hung, famed for his ever-present 70s-style sunglasses and swept-forward bowl haircut, was detained in the upmarket Repulse Bay district.

"The investigation revealed that the arrested man was suspected to have laundered more than 100 million Hong Kong dollars through four local bank accounts from January 2007 to July 2012," a police statement said, identifying Kwok only by his surname and age of 59.

Local media images showed Kwok in the back of a car looking relaxed in a black suit jacket and trademark sepia-tinted sunglasses after being arrested.

Kwok grabbed headlines in 2012 after he was reportedly seen dining with a campaign director for Leung Chun-ying, who was then a candidate for the city's leadership and secured the post later that year.

Kwok was again in the spotlight in 2015 when he was reportedly punched in the face by a mystery attacker while having afternoon tea at Hong Kong's luxury Peninsula Hotel.

Kwok brushed off the incident, saying he had bumped into a table edge.

Local media said the attack was related either to a dispute over his mistress, or to financial problems with his Macau business.

Before his arrest Wednesday, Kwok was on police bail after being arrested in July 2016 for "conspiracy to commit criminal intimidation, conspiracy to wound with intent and conspiracy to blackmail".

While Hong Kong prides itself on the rule of law, it has also been a hotbed for triad organized crime networks.

During mass pro-democracy protests in 2014, the police and government were forced to deny allegations that they were working with criminals after masked thugs attacked protesters in Mongkok, a known center of triad activity.