Veteran editors said the Communist Party wanted to make sure the media would not cause any trouble ahead of this year's 100th anniversary of the 1911 revolution and 90th anniversary of the establishment of the party, and next year's 18th party congress, and it planned to get rid of outspoken voices in the media.

The government was also alarmed by an increase in social problems including forced evictions, land disputes and mass protests, plus international attention on internet censorship and human rights, Chang said, citing Google and Nobel Peace Prize winner Liu Xiaobo . Such incidents showed how important it was to control public opinion.

A senior journalist said the propaganda authorities issued directives at the beginning of this year ordering the media to play down social problems and disasters, not to report on calls for political reform and forced evictions, and to be careful in reporting on housing prices, corruption and emergencies. They also began sending inspection teams to key Beijing and regional newspapers, starting with the Southern Daily Group, a publisher of some of the mainland's best-known newspapers and a target of censorship in recent years.

Chang is the latest in a string of cases in which media employees have been sacked for 'inaccurate' reports or running controversial and outspoken articles. Peng Xiaoyun , an opinion editor at Guangzhou-based Time Weekly, was put on involuntary leave after running a special report mentioning milk safety activist Zhao Lianhai and several people who signed the Charter 08 political manifesto.

Peng wrote on her blog that it had become a trend where journalists who stuck to their journalistic values were forced to quit or go on leave, which signalled to society that they were deprived of their rights.

A senior editor who declined to be named said newspaper managers were now more bureaucratic and political compared to previous journalists-turned-managers. Stricter media censorship had driven away passionate and ethical journalists.

'The authorities have become increasingly incompetent in censoring the media,' Chang said. 'They believe that the traditional way of bottling up the media will stifle social unrest at an early stage, and social stability is their top priority.

'However, it's this kind of policy that harms social stability. I am worried that the pent-up pressure will explode one day.'

More than 1,600 people including media workers and scholars signed their names to an online protest about Chang's sacking and the news was circulated widely on microblogs. Several lawyers, including Zhang Sizhi and Pu Zhiqiang , offered to help Chang if he decided to sue over his dismissal.

Ye Du , a Guangzhou-based media analyst who signed his name to support Chang, said that sacking journalists was no longer a quiet procedure because of an awakening civil society and the emergence of new media, especially microblog services.

'When the traditional media is tightly controlled, the new media reflects true voices,' Ye said.

Chang has a reputation for writing about political and social topics including democracy, media censorship, the failures of government policy and Tibet . His writing is considered logical and not radical.

He is determined to continue writing. 'My freedom of expressing my own views shouldn't be taken away,' Chang said. 'I am not sure how effective my commentaries are but I believe every little effort helps.'