Image copyright EPA Image caption Joshua Wong attends a rally in Hong Kong in April 2016 Image caption Thousands of protesters took to the streets in March to demand free elections
A Hong Kong court has jailed 20-year-old Joshua Wong for 17 months under the national security law, in one of the city’s toughest sentences yet handed down to an activist.
The former pupil at Chinese-run Wing Yat Chung High School was found guilty on six charges, including unlawful assembly, in a controversial case.
He was among a group of students who staged a sit-in at a police station in April 2014.
Wong had been due to be released in late August, and could be released on parole after seven months.
His supporters said the minimum sentence was 30 months.
Opinion is divided in Hong Kong over how to handle such cases. Many believe it would be better to let courts rule and show they are independent of political control.
Others say the verdicts have been too harsh.
In August 2014, more than 100,000 people took to the streets of Hong Kong after the government failed to respond to a call for universal suffrage.
Later that month, a protest of more than half a million people took place.
In September that year, protesters occupied Admiralty, the headquarters of the Hong Kong government, for more than a month.
Opinion polls have also shown a growing desire for greater democracy.
The Hong Kong government has said it will defy a Beijing-backed ruling requiring the city to hand over a fair majority of its seats to pro-Beijing candidates.
The Chinese government rules Hong Kong under a “one country, two systems” formula which guarantees the city a high degree of autonomy until 2047, and the right to elect its own leader and parliament.
But Beijing has said anyone who “wields the authority of the city to cause trouble” could be prosecuted.
The government says Wong acted to “stop the autonomous development of Hong Kong and undermine Hong Kong’s social order”, and will not tolerate attempts to unsettle the government.
The repeated arrests of student leaders, like Wong, who have supported non-violent non-political protests, have made the student movement more focused on political issues, BBC Hong Kong correspondent Matthew Price says.
“In the past their main focus has been really largely local issues, human rights, and that is why the judicial system in Hong Kong has been so careful about prosecuting them.
“The decision over what sentence to impose has inevitably been the flashpoint in the Wong case,” he adds.