Hong Kong  - More than 1,300 Hong Kong journalists Wednesday joined in a signature campaign accusing China of "blatant trampling on press freedom."

The campaign, featuring full-page advertisements in Hong Kong newspapers, follows the detention and beating of reporters from the former British colony sent to cover news events in China.

Three television journalists were detained and beaten up as they tried to cover ethnic unrest in the western city of Urumqi in September and were later accused of inciting unrest among protestors.

In a separate incident, another Hong Kong TV journalist was accused of possessing drugs in what she claimed was a ploy to prevent her covering the trial of an anti-corruption campaigner.

Advertisements condemning the actions have been taken out by the Hong Kong Journalists Association and the Foreign Correspondents' Club in Hong Kong one day ahead of Chinese National Day celebrations.

The advertisements, carrying the names of 1,300-plus signatories, said journalists were "angered by such violent stoppage of news coverage and blatant trampling on press freedom."

They call on both the Sichuan and Xinjiang provincial governments to investigate the incidents, stop repression, pledge themselves to uphold press freedoms and punish guilty officials.

The advertisement also calls for the Chinese government to abolish rules requiring journalists to apply for press permits to cover news in China and to open up dialogue with front-line journalists.

Hundreds of people marched in Hong Kong earlier this month to protest over the incident in Urumqi.

A poll by the Chinese University of Hong Kong Tuesday found support for the Beijing government in the city of 7 million had fallen to its lowest level in almost two years following the incident.

Hong Kong, which reverted to Chinese sovereignty in 1997, has a free press and enjoys freedom of speech as well as political and judicial autonomy denied to people elsewhere in mainland China.