A well-known Hong Kong pop singer and pro-democracy proponent was arrested Monday for performing songs at a political rally three years ago.

Hong Kong’s anti-corruption commission said Anthony Wong urged attendees at the rally to vote for pro-democracy candidate Au Nok-hin.

Au, who won, was also charged for promoting the show and saying Wong would perform. He has been in jail since March on other charges.

The anti-corruption commission said that providing refreshments and entertainment at a political rally was "corrupt conduct and a serious offense."

Wong, 59, was later released on bail. There has been no comment from him.

Wong has been a popular singer since the 1980s when he was one half of the Tat Ming Pair. He later went solo.

He backed the 2019 pro-democracy protesters, as well as the 2014 so-called Umbrella Revolution against what many saw as restrictive changes by the Chinese Communist Party in the way Hong Kong held elections.

After his support, Wong was banned from performing in China, and his music was deleted from streaming services.

Wong and Au were expected to appear in court on Thursday.