Wong, who is already serving a prison sentence for subversion, is one of the most recognisable faces of Hong Kong's now-quashed democracy movement.

The 28-year-old became a household name during student-led protests more than a decade ago and was also involved in the huge and sometimes violent democracy rallies in 2019 that triggered the imposition of the national security law the following year.

Wong was accused on Friday of asking foreign countries or individuals and institutions to "impose sanctions or blockade, or engage in other hostile activities" against Hong Kong and China, according to a charge sheet seen by AFP.

It said Wong, the self-exiled activist Nathan Law and others also requested that foreign entities "seriously disrupt the formulation and implementation of laws or policies" in Hong Kong and China.

These actions in 2020 were likely to cause "serious consequences", the charge sheet said.

The charge can carry a sentence of up to life imprisonment.

Rights groups said the move was a deliberate attempt to keep Wong behind bars as long as possible.

Human Rights Watch called the decision to charge Wong "arbitrary, cruel, and outrageous" and urged governments around the world to push for his release.

Amnesty International also criticised the new charge.

"Hong Kong's National Security Law is turning five years old at the end of the month, and these new charges against Joshua Wong show that its capacity to be used by the Hong Kong authorities to threaten human rights in the city is as potent and present as ever," Amnesty International's China Director Sarah Brooks said.

China and Hong Kong say the law was needed to curb political unrest, while critics say it has crushed once-vibrant civil society as well as political opposition in the financial hub.

Wong appeared in court but did not speak except to acknowledge the charge, local media reports said.

Law declined to comment when reached by AFP.

The case was adjourned until August 8.