Chang Tieh-chih, former editor of Hong Kong's City magazine, was turned back by immigration officers after he arrived at the city's international airport, en route to a literary conference, according to his Twitter account.
"So in the end, I was refused entry to Hong Kong at the airport," Chang tweeted.
Chang, 45, isn't the first non-resident to be turned away from the city for supporting the 79-day Occupy Central campaign for fully democratic elections in Hong Kong.
Chen Wei-ting, a former leader of the Sunflower student protest movement that occupied the democratic island's parliament in protest at closer ties with China earlier in 2014, said he was also denied entry to the city after he tried to support the Occupy movement in person.
While Hong Kong has until recently made its immigration decisions entirely separately from the ruling Chinese Communist Party, it has begun barring political figures from outside the city in recent years.
"They have banned political figures like us from Taiwan from entering Hong Kong in the past; the excuse they gave was that we were en route to attend a political and social movement," Chen told RFA on Wednesday.
"It seems they want to further control ties between residents of Taiwan and Hong Kong now," he said. "They are basically now operating on the same principles as mainland China."
He said the decision to bar him from the city didn't originate in Hong Kong.
"The immigration officer who denied me entry at the time was very clear about that; he said that Hong Kong officials had no power in the matter, because of the political factors," Chen said.
An official with Taiwan's Mainland Affairs Council said the government has requested clarification of the decision to bar Chang from the Hong Kong authorities.
"I wish the Hong Kong government would embrace non-government exchanges between our people, to avoid damaging the current good relationship or bilateral ties," the official said.
In Hong Kong, Civic Party lawmaker Kwok Ka-ki said Chang was likely denied entry because some of his writings hadn't gone down well in Beijing.
"Things have gotten to the point where an ordinary guy from Taiwan gets into trouble, probably because of some articles he wrote," Kwok said. "I have reason to believe that other influences are at work here, including mainland government ones, behind the decision not to allow Chang into Hong Kong."
In October, immigration authorities in Hong Kong denied entry to a U.K. ruling Conservative Party human rights activist amid apparent concerns that he would visit three jailed Occupy Central student leaders in the former British colony.
Benedict Rogers, deputy chair of the party's human rights commission, was escorted onto a plane back to Thailand, where he had come from, according to his lawyer.
Rogers said he had been warned informally by Chinese officials that he wouldn't be allowed to enter the former British colony, which has maintained its own immigration controls since its handover to China in 1997.
Rogers told the SCMP that he had had a number of indirect warnings from the Chinese embassy in London, amid official fears that he intended to visit the jailed student leaders of the 2014 democracy movement, Joshua Wong, Nathan Law and Alex Chow.
Chang's refusal of entry came after the legal head of Beijing's Liaison Office in Hong Kong warned the city that its laws are subordinate to those of the People's Republic.
"Since July 1, 1997, Hong Kong's political color undoubtedly became red, meaning it has become part of red China," Wang Zhenmin told a conference in the city on Monday.
"So there is no question of whether Hong Kong is 'becoming red' because Hong Kong has already been red since 1997, when it came under the leadership of the Chinese Communist Party," Wang said.
Under the terms of the 1997 handover, Hong Kong was promised the continuation of its existing freedoms and way of life for 50 years under Chinese rule.
But U.S. and U.K. officials have warned that Beijing's increasingly hands-on approach is eroding the city's promised autonomy, known as the "one country, two systems" framework.
The cross-border detentions of five Hong Kong booksellers, and the barring of six directly elected pro-democracy lawmakers after Beijing intervened to rule their oaths of allegiance invalid have also thrown up doubts about the city's judicial independence.
Reported by Lam Kwok-lap for RFA's Cantonese Service. Translated and edited by Luisetta Mudie.
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