Wong's new book Sun Yat-sen Before 30, which is already on sale in Hong Kong, argues that Sun's Westernised education during the nine years that he lived in this city shaped his political ideas.

Wong said that whether Beijing could accept that fact would be an indication of whether the current leadership is more liberal than those of the past.

Early signs suggest they do - Wong's comments came days after an article in Beijing's Renmin Ribao declared that Sun's revolutionary thoughts came from Hong Kong. In a prominently placed article, the paper's reporter quoted an official of the Hong Kong Museum of History as saying that a colonial education had taught Sun about the modern world.

Wong said: 'Without Hong Kong, there would not be the Sun Yat-sen we all know about. Hong Kong provided him with modern concepts.'

Historic materials included in the book include an examination question prepared by teachers at Central Government School, where Sun studied, about sanitary problems.

Wong said the issue probably had an impact on Sun, whose home village of Cuiheng, in Guangdong province, had serious hygiene problems.

The book also contains a letter written by Sun in which he referred to his studies at Diocesan Home, now the Diocesan schools.

The book raises doubts about a popular belief that he was once a prisoner at Victoria Prison.

'As a historian, my motives are pure,' Wong said. 'I want to express my sincerity towards the reunification of China. People ought to know what Sun Yat-sen is all about, first.'

Wong, who now teaches at the University of Sydney, argues that Chinese on both sides of the Taiwan Strait must have a shared vision of the country's history before reunification can work.

According to Lai Yiu-keung, who edited Wong's book, the Beijing publisher had known of the subject of Wong's book for half a year but did not tell the author about the need to get official approval until a few weeks ago.

Wong fears the book will be delayed until after Chinese communities around the world celebrate the revolution's 100th anniversary.

'Originally a publisher in Beijing said they would publish it. But later they said it needed to be sent for approval. The story is about things that happened before the Republic of China was founded. Why should mainlanders not read the book?'

Mainland authorities could not be reached for comment.

Wong's previous works include one about Sun's kidnapping in London after he fled Canton in the wake of a failed uprising in 1895.

The 65-year-old scholar said he hoped that by revealing history, he could facilitate understanding between the people of Taiwan and the mainland.

'Sun is someone who is accepted by every Chinese as the founder of modern China. He is the best icon for dialogue between the people on both sides of the strait,' he said.

Wong recently visited Hong Kong, speaking at universities about his book. He said students ought to know that Sun's vision of a modern China has still not been achieved.

'The hardware is there. But there is no software - the mindset.'