CANBERRA (Reuters) – More than 90 Australian authors signed a letter on Thursday decrying China's refusal to grant a visa to one of the country's most celebrated writers because he was HIV-positive, a move that Beijing defended.

Robert Dessaix, whose 1996 novel "Night Letters" dealt with the European travels of a man diagnosed with an incurable disease, was refused permission by Chinese authorities to attend the International Literary Festival in Shanghai on health grounds.

More than 90 other writers, including Nobel laureate J.M. Coetzee and Booker Prize winner Thomas Keneally, who penned "Schindler's Ark," rallied to Dessaix's support, demanding a public apology from Beijing.

"This was an act of discrimination that appears to be founded in fear or ignorance and is behavior unworthy of any nation that desires to be seen as enlightened and civilized," the joint letter said.

"Mr Dessaix, an internationally published and acclaimed author, has been unjustly left out of the Australian government supported Writers' Tour currently under way in China," the group from The Australian Society of Authors wrote.

Dessaix's visa refusal follows strains with China over the arrest in Shanghai of an Australian mining executive and Canberra's decision last year to grant a visa to a high-profile Chinese ethnic separatist leader.

A Chinese Foreign Ministry spokesman, Qin Gang, told reporters in Beijing he was unfamiliar with Dessaix's case and why he was refused a visa, but defended China's rules barring HIV-positive people from entering the country.

"If he is HIV-positive, then based on China's relevant regulations, he cannot enter China.

"I hope the Australian side and the author himself will be able to understand this."

The spokesman added: "In China, AIDS sufferers and HIV-positive people are respected and their legitimate rights protected."

Dessaix, 65, is the author of the poetic "Night Letters" and "Corfu." The first novel was based around letters written home from a Venice hotel room, pondering Italian history, philosophy and questions of human fate, including his own.

Dessaix's autobiography, "A Mother's Disgrace," was published in 1994.

"I am not a threat. I don't write on political issues. I feel I've been spat on," Dessaix told The Age newspaper. "I live in Australia and I can come home to a civilized place where people care."

(Reporting by Rob Taylor and by Chris Buckley in Beijing; Editing by Sugita Katyal)