Founded by veteran pro-democracy protest leader Han Dongfang in 1994, China Labour Bulletin (CLB) said on its site Thursday that it "can no longer maintain operations".

It said it would dissolve "due to financial difficulties and debt issues" and would stop updating its website, according to an archived webpage seen by AFP. Its social media platforms have also been removed.

The website monitored the Chinese labour movement from Hong Kong, tracking and mapping worker unrest for three decades, closely watching the biggest labour disputes related to China and documenting worker strikes across the country.

An AFP reporter visited CLB's publicly known office address in Hong Kong on Friday afternoon and saw it closed for business with its sign removed.

The residence's landlord took the office back at least a month ago, security staff at the scene told AFP.

Before the group shut down, it reposted on social media a report analysing international workers' strikes that it had jointly researched.

Its website could be accessed as normal on Thursday.

The group's founder Han was a leading protester and unionist in pro-democracy demonstrations in Beijing in 1989, which eventually turned into a bloody crackdown at Tiananmen Square.

He was jailed for his role in the protests and moved to Hong Kong in the 1990s where he started a decades-long effort to promote and defend Chinese workers' rights remotely.

In May, he indicated on social media that he and his team would continue "without ending" their tracking work.

"Let's keep our faith up at this abnormal time and continue our important work," he wrote.

But on Friday he told Taiwan's Central News Agency the decision to dissolve was made by himself and "due to financial problems", adding that he would stay in Hong Kong.

Han reportedly declined to answer other questions.