The activists have been identified as Lee Cheuk-yan, 69, and Chow Hang-tung, 41.

They face a maximum sentence of 10 years in prison following their convictions under the national security law introduced by China. The date for sentencing has not yet been announced.

According to a summary of the verdict quoted by the BBC, Lee and Chow were found guilty of having "incited other persons to organise, plan, commit or participate in acts by unlawful means with a view to subverting the state power."

A third defendant, Albert Ho, 74, was found guilty in January in the same case.

For decades, Hong Kong was the only place in China where people were permitted to publicly gather to commemorate the deadly 1989 crackdown on pro-democracy protesters in and around Beijing's Tiananmen Square.

However, authorities banned the annual vigils in 2020, initially citing coronavirus-related restrictions. The gatherings have not been permitted since.

Reacting to the convictions, Elaine Pearson, Asia director at Human Rights Watch, said the verdicts demonstrated how "public displays of mourning have become a crime in Hong Kong."