Chan has been serving two concurrent sentences over offences related to unauthorised protests in October 2019.
Former Hong Kong protest coalition leader Figo Chan has been charged with allegedly participating in an unauthorised demonstration that took place on September 15, 2019 on Hong Kong Island.
The activist was charged on Monday whilst in jail, a post made to his Facebook Page said.
Chan is concurrently serving an 18-month sentence over another unauthorised assembly on National Day in 2019 and a 16-month sentence over another protest on October 20 the same year.
Chan has been in custody since May, after pleading guilty to the offence alongside other democrats.
Police objected to an application by the now-defunct pro-democracy protest coalition – the Civil Human Rights Front – to organise a march on Hong Kong Island on September 15, 2019, during the height of the anti China extradition bill protests and unrest.
The group disbanded in August, citing “unprecedented challenges.”
The group cancelled the march but thousands turned up anyway, with police deploying tear gas and water canon as some demonstrators hurled Molotov cocktails and bricks.
Reporting by Sean Tyler Chan