Hundreds, and possibly thousands, of students died in the Tiananmen Square area of Beijing in June 1989 when the Chinese government sent in troops to crush a pro-democracy uprising and preserve one-party rule in China.

Carrying banners and shouting pro-democracy slogans, the demonstrators marched from Victoria Park in Hong Kong's Causeway Bay to the central government offices, demanding greater freedoms in China and an official apology for the killings.

The march was organised by the Alliance in Support of Patriotic Democratic Movements in China and was a prelude to a mass candlelit vigil in Victoria Park on the anniversary of the crackdown, which attracts tens of thousands of people every year.

Alliance chairman Lee Cheuk-yan said his members feared Hong Kong's incoming chief executive, Beijing-appointed Leung Chun-ying, would further restrict freedom of expression when he takes office from July 1.

Hong Kong, a former British colony that retains semi-autonomous status since reverting to Chinese sovereignty in 1997, is the only city on Chinese soil where the anniversary of the massacre is publicly commemorated.