Hong Kong business tycoon Jimmy Lai has been arrested for suspected collusion with foreign forces, his aide has said.
Mark Simon said the businessman was held under the controversial national security law imposed by China in June.
Mr Lai has been a prominent supporter of the pro-democracy protests that erupted in Hong Kong last year.
In February, the 71-year-old who also holds UK citizenship was charged with illegal assembly and intimidation. He was later granted police bail.
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“Jimmy Lai is being arrested for collusion with foreign powers at this time,” said Mr Simon, an executive at Mr Lai’s media firm Next Digital.
According to local media, Hong Kong police have also entered the building of his media company, searching the offices.