Tiananmen Square protest leader Wang Dan and Hong Kong political figures have urged the younger generation to make serious efforts to dig out the truth of the 1989 crackdown before debating it. The calls came as students from Hong Kong and the mainland had a heated debate yesterday over the June 4, 1989, crackdown. In a forum at the University of Hong Kong in the run-up to the 20th anniversary of Beijing's crackdown, the students debated whether it was a 'massacre'. 'Not a drop of blood was spilled in Tiananmen,' an exchange student from the mainland said at the forum. 'Why were some men of the People's Liberation Army killed by the students if it was a 'peaceful' demonstration?' asked the student, giving his name as Qu. His remarks were drowned out by boos while somebody yelled: 'How can you be a university student?' A Hong Kong student shot back at Qu: 'There were overwhelming reports on the bloody incident at the time. Do you mean the whole world lied and that what you say is true?' In a letter to the city's university students released yesterday, exiled dissident Dr Wang said it would be difficult for people to get a good understanding, two decades after the crackdown, of what happened. 'Some [misunderstandings] were due to lack of information, while some were because the government has intentionally confused right and wrong,' he wrote. 'There is too much misunderstanding and misleading information.' Veteran journalist Ching Cheong, who was released on parole from a Guangzhou prison early last year after serving time for espionage, said opinions could differ but truth could not be distorted. Mainland authorities had done much to distort history over the years, he said. Civic Party lawmaker Alan Leong Kah-kit called for the students to understand the incident better before entering a debate. 'Discussions should be based on facts,' Mr Leong said. 'There can be many observations in the discussion but there is only one fact.' The university's student union will hold a poll next Tuesday on a motion stating: 'The Central People's Government of the People's Republic of China must vindicate the 1989 democratic movement, and be held accountable for the June 4 massacre.' The result will be taken as the official stance of the student union on the June 4 crackdown. Student union president Ayo Chan Yi-ngok was also urged to apologise for an earlier remark. Mr Chan, who said earlier that one of the Tiananmen protest leaders was a 'runaway student leader', said he was accountable but later added that he could not recall whether he had said the controversial words.