Hong Kong police arrested 23-year-old Joshua Wong on Thursday, a man believed to be behind the city's riots last year. 

A 74-year-old man was also arrested for involvement in the riots. Both men stand accused of "knowingly taking part in an unauthorized assembly". 

Wong is also accused of breaching Hong Kong's Face Covering Regulation. 

The two are expected to appear in the city's Eastern Court on September 30.