Hong Kong activist Joshua Wong and two other student leaders of huge pro-democracy protests in 2014 are bracing for possible prison sentences in an appeal court decision.

The three-judge panel is due to issue its ruling Thursday on a prosecution request for stiffer sentences following a lower court decision that let them avoid prison.

The three were found guilty of leading or encouraging an illegal rally in September 2014 that kicked off the demonstrations known as the "Umbrella Movement."

Wong became famous for his role in the protests because he was just 17 and still in high school at the time.

He was given community service last year. But the appeal court judges were expected to send him to prison, following their decision in a similar case this week.