A Hong Kong man on Monday pleaded guilty to sedition for wearing a T-shirt with a protest slogan, becoming the first person convicted under the city's new national security law passed in March.

Chu Kai-pong, 27, pleaded guilty to one count of "doing with a seditious intention an act."

Under the new security law, the maximum sentence for the offense has been expanded from two years to seven years in prison and could even go up to 10 years if "collusion with foreign forces" was found to be involved.