Protesters marched through the center of Hong Kong in their thousands, demanding to know the whereabouts of five missing people linked to a publisher that has been critical of the Beijing leadership.

Clad in yellow and holding aloft yellow umbrellas - the symbol of the 2014 pro-democracy protests that brought parts of the city to a standstill - demonstrators gathered outside the city government's headquarters.

Five people have gone missing in recent weeks, the latest being Lee Bo. Like the other four, Lee is associated with the publisher Mighty Current. Along with Causeway Bay Books, of which Lee is also a shareholder, the publisher is known for releasing gossipy titles about Chinese political scandals and the private lives of the elite.

One upcoming book was expected to feature details about an old "girlfriend or mistress" of Chinse President Xi Jinping.

"No to political kidnap!" demonstrators chanted, brandishing banners featuring the words "Where are they?" as they headed toward China's representative office the Western district.

Gossip about political leaders

Organizers said 6,000 people took part in the protest, while police put the number at 3,500.

The disappearances have created a mood of nervousness among publishers and booksellers, with some pulling books that are critical of Beijing's political elite from their shelves.

The disappearances come amid mounting concern that Beijing is seeking to tighten its grip in Hong Kong and clamp down on dissent.

Chinese law enforcement officers have no official right to operate in Hong Kong, but supporters of the disappeared individuals fear they have been kidnapped and taken to the mainland.

"This is a milestone for suppression," said rally co-organizer Lee Cheuk-Yan. "This is is a milestone for us also; that we need to come out and protect our freedom and our 'One country, two systems'."

The former British colony was handed back to China in 1997, but was granted constitutional freedoms and autonomy - intended to preserve the territory's freedoms and way of life - for 50 years.

rc/gsw (AFP, Reuters)