About 30 activists rallied Wednesday to demand the release of Nobel Peace Prize laureate Liu Xiaobo, who was diagnosed with cancer after years of imprisonment in mainland China, on the eve of Chinese President Xi Jinping's visit to Hong Kong to mark the 20th anniversary of its handover.

The protesters circled the Golden Bauhinia statue, a gift from China signifying its sovereignty over Hong Kong, while calling for the release of Liu and other dissidents and for democracy for Hong Kong through "true universal suffrage."

Some protesters chained themselves to the 6-meter-high flower statue, which was draped with a black banner carrying slogans.

"This is the moment to tell Xi Jinping our wishes before he arrives in Hong Kong," legislator Nathan Law of youth group Demosisto said.

"There are plenty of placards put up across the territory to welcome Xi's visit. But we want to tell the truth about Hong Kong after the handover, that democracy has yet to come, while human rights and freedom continue to suffer," Law said.

Liu, a lecturer at Beijing Normal University, was sentenced to 11 years in prison in December 2009 for "inciting subversion of state power" by helping draft a blueprint for political change, calling for democracy, human rights and the rule of law in China.

His wife Liu Xia has been under house arrest in Beijing without trial since he was awarded the Nobel Prize in 2010.

The protesters' call for public support at the site was futile as police cordoned off the area nearby and later removed them.

Security measures have been beefed up days ahead of Xi's visit, particularly in the Wan Chai area of Hong Kong Island where Xi is expected to take accommodation and preside over the inauguration ceremony of the territory's new administration on Saturday.