A pro-democracy activist from Hong Kong has been barred from traveling to the United States to receive a major human rights award, according to court documents reviewed by The Daily Beast.

Joshua Wong, who led major student protests against Beijing in 2014, was sentenced in January to three months in prison for his role leading the demonstrations.

He is appealing the conviction, and out on bail. As a condition of his bail, Wong surrendered his passport to the court. Documents show the court has denied his request to travel to the United States to receive the Lantos prize, an award from an American foundation honoring former House Foreign Affairs Committee chair Tom Lantos. Prior recipients of the prize include Hillary Clinton, the Dalai Lama, and Elie Wiesel. Wong, whose activist work was the subject of a 2017 Netflix documentary, would have accepted the award in Washington next month had he been able to travel.

Human rights advocates say Wong’s travel restrictions are evidence of an increasingly draconian crackdown on dissent. Hong Kong was long viewed as a haven for freedom of speech; but Wong’s politicized prosecution and strict bail terms are seen as evidence that the city is complying with Beijing’s efforts to silence its critics.

“I just hope people realize that that’s the new tactics used under Chinese imperialism,” Wong told The Daily Beast. “They just restricted activists from traveling abroad to explain about the situation of Hong Kong, and at the same time they also try to ban journalists from entering Hong Kong. So it’s just a restriction and erosion of the free flow of information.”

Wong was referring to Hong Kong’s refusal to renew a Financial Times editor’s work visa, which has sparked concerns among press freedom advocates and the business community.

A spokesperson for the Chinese embassy in Washington did not respond to a request for comment. In its ruling, the court wrote that letting Wong travel could undermine “public confidence in the due administration of justice.”

Katrina Lantos Swett, the president of the Lantos Foundation, called the development disturbing.

“This fearful and repressive conduct by China is shameful and embarrassing,” she said. “It is not a good look for a nation that aspires to be seen as a rising superpower. China will never achieve its goals as long as it continues to crush democracy and trample basic human rights.”

Human rights advocates say Wong’s inability to leave Hong Kong is deeply concerning.

“It’s just one more example of how Hong Kong has been subsumed into the Chinese communist system,” said Marion Smith, the head of the Victims of Communism Memorial Foundation. “Those are the kinds of restrictions on travel of sensitive individuals that are commonplace in the PRC, but new in Hong Kong.”

“He deserves to be recognized, and it is no surprise that China wants to prevent it,” he added.