The International Federation of Journalists has expressed "grave concerns" over the arrest in China of a Hong Kong journalist.
Ching Cheong is The Straits Times' chief China correspondent
China has accused Ching Cheong, a correspondent for Singapore's Straits Times, of spying.
The IFJ said that while Chinese journalists were often jailed, Beijing has refrained from jailing journalists working for foreign news outlets.
The IFJ has called for Mr Ching's immediate release.
"The latest crackdown by Chinese authorities on foreign journalists and media outlets is indicative of their systematic policy of silencing the media," the president of the Brussels-based watchdog, Christopher Warren, said in a statement.
Mr Ching, 55, was detained on 22 April in the southern Chinese city of Guangzhou.
China's foreign ministry said he had admitted to the spying charge.
His wife, Mary Lau, said he had travelled to China to collect secret papers linked to the former Chinese leader, Zhao Ziyang. Mr Zhao, who died in January, was ousted for opposing the suppression of pro-democracy demonstrators in Tiananmen Square in 1989.
Mr Ching is a Hong Kong citizen, with permanent resident status in Singapore.
He is the second employee of a foreign news organisation to be taken into custody by President Hu Jintao's government in a year.
New York Times researcher Zhao Yan was arrested by the Chinese authorities last October and charged with revealing state secrets. He is still awaiting trial.