TAIPEI, Taiwan (AP) _ Taiwan's former top official for China affairs has been denied entry into Hong Kong, officials said today, a sign that recent tensions between Beijing and Taipei are continuing.

Chang King-yuh was denied a visa to attend an academic conference at the University of Hong Kong, where he was scheduled to deliver an address Thursday on the topic of reunification between Taiwan and China.

Chang, a policy adviser to President Lee Teng-hui, helped draft policy toward China as head of the Cabinet's Mainland Affairs Council until last year.

Fredrick Fung, general education coordinator for the University of Hong Kong, said immigration officials gave no reasons for the rejection of the visa request.

``It's an academic exchange, but officials may find the topic, which is on China-Taiwan relations, too sensitive at this time,'' Fung said.

Chang was granted permission to visit Hong Kong last May while he was still a Cabinet official in what was considered a sign that politics would not affect Taiwan's relations with Hong Kong.

``Now that he's retired and is a regular citizen, we would think that he should have no problem getting the approval,'' Fung said.

Felix Tsui, a spokesman for the Hong Kong Immigration Department, said that as a matter of policy, the department does not comment on individual cases.

After Hong Kong's handover from British to Chinese rule in 1997, Taiwan was allowed to continue to station de-facto diplomats and operate a visa-issuing office in Hong Kong, which is a crucial channel for Taiwanese trade, travel and investment in China.

But by refusing a visa to Chang, China appears to be tightening the screws diplomatically on Taiwan while separately ratcheting up its threats to use force to reunify the island with the mainland. Taiwan and China separated in a 1949 civil war, and Beijing still views Taiwan as a renegade province.

Ties between Taiwan and China have become strained since last month, when President Lee infuriated Beijing by saying matters between the two should be conducted on a ``state-to-state'' basis.

China sees the statement as a step towards the island's independence and has threatened military action should Taiwan ever declare formal independence.

A Hong Kong newspaper today reported that Beijing leadership has decided to use military force against Taiwan if Taipei refuses to repudiate Lee's statement.

The South China Morning Post said China was considering an ``appropriate degree of force,'' but the only option mentioned was an invasion and temporary occupation of an outlying island held by Taipei.