Joshua Wong has described his fear of being arrested by Hong Kong authorities while speaking in a virtual appearance at British book festival.
The 23-year-old said his very participation in the event might put him at risk, but that it was his duty to keep speaking out about China's tightening grip on the semi-autonomous city.
Mr Wong said that two hours before he appeared at the Edinburgh International Book Festival, he was tailed by an unknown car with a China-Hong Kong licence.
While visiting Victoria Peak in Hong Kong with friends, he said he was photographed and verbally abused by a "pro-Beijing gang".
"Those are the common tactics that they use to target pro-democracy activists," he said.
Mr Wong said the price he paid in being under surveillance was "comparatively small" compared to protesters shot with live rounds during demonstrations last year.
Pro-democracy activist Joshua Wong (C) makes a speech on a street in Hong Kong (AAP) Source: Kydpl Kyodo
But he said it was hard to plan for the future under the threat of the national security law China imposed on Hong Kong in June in response to last year's huge and often violent pro-democracy protests.
He said it was "already a kind of miracle" that he was still at liberty to speak at such an international event.
"Every day I sleep, I also worry will the government come to arrest me immediately, or the day after, storm into my house at 5:00 am just like experienced by Jimmy Lai," he said.
Media mogul Lai was among 10 people detained under the law earlier this month, and the newsroom of his Apple Daily was searched.
'Uphill battle'
Prominent activist Agnes Chow, who like Mr Wong was a key figure in the "Umbrella Movement", was also arrested. Both were released on bail.
Mr Wong says the pro-democracy movement was only asking for the autonomy that Beijing promised Hong Kong when it was handed back from Britain in 1997.
"We are not asking something that goes too far," he said in the interview conducted by Sophie Richardson, China director of Human Rights Watch.
Mr Wong said he saw "no chance" for Hong Kong to have free elections under Chinese President Xi Jinping, but said activists should press on, adding that he still had hope in the people of Hong Kong.
"Hong Kong is not Hong Kong any more, but with the spirit of Hong Kongers we still go forward in this uphill battle," he said.
