By Vaudine England
BBC News, Hong Kong
Cardinal Zen, an advocate of democracy, wants 1989 re-examined.
The former leader of Hong Kong's Catholic Church has urged China to reassess its verdict on the 1989 Tiananmen killings.
Cardinal Joseph Zen said he wanted an official inquiry into what happened so future generations could tell the difference between right and wrong.
Hong Kong, a former British colony, is the only place under Chinese rule where memorials to the massacre are held.
The Cardinal, retired from his Hong Kong role, is an adviser to the Pope.
In a talk at Hong Kong's Foreign Correspondents' Club, the cardinal said he wanted to see an official re-examination of the bloody crackdown of 20 years ago this week.
"I hope they really consider seriously the possibility of a reassessment of the verdict," Mr Zen said.
"It will not damage anyone, but would be to the advantage of the whole nation," he said.
China's official line on the Tiananmen massacre, in which hundreds, possibly thousands, of demonstrators and civilians were killed, is that the protests threatened Communist Party rule and had to be quelled.
Asked by AFP news agency when or if he thought the Chinese government would soften its stance, Mr Zen said: "Things in China are unpredictable. It may happen tomorrow or still take 20 years."
Hong Kong's role
Many at Sunday's protest wore black and white, to symbolise mourning
A strong advocate of democracy, Cardinal Zen usually opens the 4 June candlelight vigil in Hong Kong, held every year to mark the massacre.
This year he will be in Rome, but held a special mass for victims last Friday.
Organisers are expecting a strong turnout this year, in part because of comments made by Hong Kong's chief executive, Donald Tsang, which appeared to airbrush history.
Claiming to speak for all Hong Kong people, Mr Tsang said China's economic development should be taken into account when assessing the events of 20 years ago.
The outspoken pro-democracy figure Leung Kwok-hung, known as Longhair, believes Mr Tsang's comments will bring more people to the vigil.
Thousands of people joined a march in Hong Kong on Sunday to mark the forthcoming anniversary of the Tiananmen killings, in one of the few such events on Chinese soil.