Tens of thousands of people are due to attend an annual candlelight vigil in Hong Kong on Thursday to mark Beijing's Tiananmen Square crackdown in 1989 as tension lingers in the financial hub from its pro-democracy protests last year.

More than six months since Hong Kong police demolished the last encampments of protesters agitating for full democracy in the city, the organizers of this year's June 4 vigil are aiming to link the events, which is likely to antagonize China.

"Occupy was in a way a mini-June 4 for Hong Kong," said city legislator and vigil organizer Lee Cheuk-yan, referring to last year's Occupy Central protests.

"We should not separate our fight for democracy from that of China's. We should link up the two and fight in unity."

At the vigil this year in the city's harbor-side Victoria Park, images and symbols of Hong Kong's protests will be draped on the stage, T-shirts and posters, Lee said.

A statue of a goddess of democracy - which towered over the Tiananmen protests in 1989 - would sport a yellow umbrella - a symbol of defiance in Hong Kong last year when activists used umbrellas to shield themselves from police pepper spray and teargas.

Hong Kong, a former British colony that returned to Chinese rule in 1997 under a deal to preserve wide-ranging freedoms, is the only place on Chinese soil where commemorations of June 4 are tolerated.

Discussion of the 1989 protest, termed "counter-revolutionary" by Beijing, is taboo on the mainland.

The political temperature is rising again in Hong Kong ahead of a June 17 vote on a Beijing-vetted electoral package that democrats denounce as a sham that makes a mockery of pledges to eventually grant Hong Kong universal suffrage..

China has declined to make concessions on its blueprint for Hong Kong's next leadership election, under which a 1,200-member committee, packed with Beijing loyalists, will vet two or three candidates who will compete for votes to become the city leader.

The two pro-democracy movements - separated by a quarter of a century - have parallels but also big differences.

Police disbanded the Hong Kong protest after 79 days without serious violence, unlike the crackdown in Beijing in 1989. China has never released a death toll but estimates from human rights groups and witnesses range from several hundred to several thousand.

In Taiwan, organizers of a June 4 vigil will hold up yellow umbrellas in solidarity with Hong Kong.

"We would like to speak out for Hong Kong, for the democracy, freedom and human rights we are fighting for," said Chou Ching-chang, an organizer.