Hong Kong police arrested on Saturday about a dozen democracy activists on charges of illegal assembly in raids across the Asian financial hub, media and political sources said.

Believed to be among those detained in the swoop is prominent Democratic Party founder and senior barrister Martin Lee, 81, broadcaster RTHK reported. In all, nine former legislators were arrested.

Hong Kong police have yet to confirm the arrests, which media said related to marches on Aug. 18 and Oct. 1 last year — both days of large and at times violent protests across the city.

Media showed footage of police outside the house of publishing tycoon Jimmy Lai, a financial backer of the city's pro-democracy movement.

Lai was arrested on similar charges in late February, along with veteran activists Lee Cheuk-yan and Yeung Sum. It was unclear whether he was among those arrested on Saturday, while others named by media could not be contacted.