Prominent Hong Kong pro-democracy campaigner Joshua Wong has pleaded guilty to collusion with foreign entities, a charge that carries a maximum sentence of life in prison under Beijing's sweeping National Security Law (NSL).

The 29-year-old, who has become the poster child for political activism in Hong Kong, is already serving a sentence of four years and eight months after being convicted of subversion – another NSL violation – in late 2024.

The court said Wong would be sentenced at a later date. His earlier jail term is due to end early next year.

Wong was at the forefront of the Umbrella Movement in 2014 and massive pro-democracy protests in 2019.

The latest charge accuses Wong of conspiring with other campaigners, including exiled activist Nathan Law, to ask foreign countries and entities outside China to impose sanctions or blockades against Beijing.

These include activities that took place between July and late November 2020, the court heard. That was the year China introduced the controversial NSL, which critics say has created a climate of fear and quashed dissent in Hong Kong.

Beijing and Hong Kong authorities argue the law is necessary to maintain stability and deny it has weakened autonomy.

On Tuesday, the court heard that Wong and Law had participated in "international lobbying on numerous occasions", including via visits to the US, Germany and Italy.

The duo are among several leaders who founded the pro-democracy party Demosistō in April 2016, and ran for the Hong Kong Legislative Council elections that year.

Among other things, prosecutors on Tuesday also accused Wong, along with Law, of promoting the Hong Kong Human Rights and Democracy Act: a US federal law that came into force in November 2019, during Donald Trump's first administration. The Act compels the US government to impose sanctions against mainland China and Hong Kong officials if they are deemed responsible for human rights abuses in Hong Kong.

Even after Demosistō disbanded, Wong had maintained that he would not abandon his political stance and would continue to seek support from the international community, the prosecutors said.

Wong, dressed in a dark blue shirt and dark-rimmed glasses, did not dispute these allegations.

About 40 of Wong's supporters, including fellow activists and some of his close friends, gathered in court on Tuesday. Some shouted: "Hang in there, Joshua!"

Wong was seen smiling and nodding in response from the dock.

Tsang Kin-shing, a former member of the now-dissolved League of Social Democrats, said he hopes the court will impose a lenient sentence, noting that Wong has by now spent more than 2,000 days in prison.

Fellow activist Louis Lee said Wong and his supporters were disheartened that he was handed another NSL charge while already serving time in prison.

Wong has continued seeking out new interests while in prison, including learning how to play the guitar and working out.

"I hope everyone can learn from him," Lee says.