Friends of Hong Kong-based journalist Ching Cheong, who is accused by the mainland of spying for Taiwan, have begun collecting signatures for a petition urging the central government to give him an open and fair trial.
Former classmates and friends from the University of Hong Kong said the 'patriot and family man' they knew for decades would never spy for Taiwan.
They also questioned reports implicating Ching in a sex and money scandal. They suggested the reports were part of a smear campaign by the state against Ching, a journalist for The Straits Times of Singapore who was formally arrested last week after four months' detention.
'Ching Cheong is an upright man, a patriot, and we will never believe the charges laid against him. How can he be a spy? We are shocked, and we demand a fair trial and an early release,' said Mak Chai-ming, director of the Hong Kong University Graduates Association.
The group of friends criticised some Chinese-language media for reporting unidentified mainland sources saying Ching became involved in espionage because he needed money to keep a mistress.
They said the arrest of such a patriot had sent fear through the pro-Beijing camp.
The group has set up a website, www.chingcheong.com , featuring information on Ching, to collect signatures. More than 100 people, including politicians, academics and officials, have already signed.
But a close friend of Ching's in the pro-Beijing camp said many colleagues had shied away from such action, fearing it would force the central government to seek a harsher sentence.
'Even if the so-called evidence is false, the central government will make it stick if we continue to make it lose face,' the politician said.
Asked whether Ching should receive a fair trial, National People's Congress Standing Committee member Tsang Hin-chi questioned why people thought he had already received unfair treatment.
He said no countries in the world would disclose their state secrets. Matters involving secret information could not be disclosed to outsiders.
Li Gang , deputy director of Beijing's liaison office in Hong Kong, stressed that mainland authorities would handle the case in accordance with the law.
'The mainland will make judgment according to its law. If he has violated the law, of course he needs to accept punishment. If he didn't violate the law and is innocent, then of course he would be released.'
Mr Li did not say whether Ching could have access to his family or legal representation, as he did not work in the judicial department.