A Beijing high court rejected Hong Kong-based journalist Ching Cheong's appeal. He was sentenced in August to five years in jail on charges of spying for Taiwan - charges his supporters say were fabricated.
State media quoted the judge as saying that the original verdict was "accurate in application of the law and appropriate in meting out punishment."
Speaking outside the courthouse, Ching's older brother, Ching Hai, said he felt "sad and shocked" by the verdict. He questioned the fairness of the legal process, and said the verdict would not have stood in a mature legal system like Hong Kong's.
The head of the Hong Kong Journalists' Association, Serenade Woo, says there is a lack of evidence to convict Ching and he should be released.
"The appeal court should have to seriously re-think the judgment of the lower (court). If there is any doubt they should let Mr. Ching be released as soon as possible," she said.
Ching, who reported for the Singapore Straits Times newspaper, was detained in April 2005 in southern China. The Chinese authorities accused him of handing over state secrets to a Taiwanese foundation. Ching denied the claim.
His wife and supporters say he was in China in his capacity as a journalist, collecting documents related to the purged Chinese Communist Party leader Zhao Ziyang.
In 1989, Zhao famously expressed sympathy for the protesters during pro-democracy demonstrations on Tiananmen Square. He was later stripped of his posts and died earlier this year. Any documents relating to Zhao could be sensitive for China's leadership.
Serenade Woo says the trial is also a warning for Hong Kong and foreign journalists working in China, to watch what they write.
"They just want to send out a message to all the journalists, be cautious, otherwise you will be charged," she said.
Ching's wife says the journalist, who is 56, suffers from insomnia and stomach pains. His supporters hope authorities may release him on medical grounds.