A journalist in Gansu Province, who was detained on charges of blackmail and released after 30 days' detention, was beaten by other prisoners, the Chongqing Morning Post reported Thursday.

Zhang Yongsheng, from the Lanzhou Morning Post, was detained on January 7 on charges of blackmailing the local government through demanding money to retract negative reports and was released on bail on February 6.

The Gansu prosecutor's office confirmed on February 6 that since 2009, Zhang blackmailed 5,000 yuan from the local government.

The provincial prosecutor confirmed an administrative penalty on February 6, saying that the evidence for his crime was clear, while charges of using prostitutes were dropped due to lack of evidence.

The Chongqing Morning Post report said that Zhang was kept in a cell with 10 prisoners including suspected murderers and drug users and he was beaten by inmates after they stripped his trousers off.

The report said that after he was released, he appeared to be in bad shape.

The case began to draw public attention after an open letter began to circulate online.

The letter questioned the reasons for his detention, saying that police first said Zhang was detained for using prostitutes on January 7, and then the charge was changed to blackmail on January 14.

Zhang had been threatened previously over negative reports, according to the letter.

Public security officials called him to remove negative reports about the local government and threatened him over the phone after he turned them down, the letter added.

The Lanzhou Morning Post denied on January 29 that it had written the letter. But several media outlets reported later that they had confirmation from different sources that the newspaper did publish the letter.