Tens of thousands of people attend a candlelight vigil in Hong Kong's Victoria Park, June 4, 2006

Thousands of people have gathered in Hong Kong to remember those activists killed by Chinese forces in the 1989 crackdown on a pro-democracy demonstration in Beijing's Tiananmen Square.

Mourners held a candlelight vigil in Hong Kong's Victoria Park - the traditional site for annual gatherings marking the crackdown. Some called for Chinese leaders to officially acknowledge the incident.

Such ceremonies are forbidden in mainland China, where the government restricts information about what happened on June 4, 1989.

In Washington, the State Department called on Beijing officials to give a full accounting of the crackdown, including identifying the thousands killed and detained as well as those who have been missing since that night. U.S. officials also urged Beijing to identify people still imprisoned.

Chinese police have tightened surveillance of known dissidents and others Beijing considers a threat to peace and stability. Relatives of victims who died at Tiananmen Square say police have questioned them about their plans for the anniversary.

The exact numbers of people killed, wounded or detained in connection with the Tiananmen Square demonstration are unknown, but it is believed hundreds of activists died and thousands of others were taken into custody.

Tiananmen relatives have urged China's leadership to make gradual moves to bring justice to the victims. They also are asking the government to end restrictions on those who survived the crackdown, and their families, and allow them to collect financial assistance from home and abroad.

Communist authorities in Beijing have refused to change their official view that the Tiananmen Square protesters were engaging in a counter-revolutionary riot.