Liu Hu became widely known more than 10 years ago for his reports on graft among high-profile figures in the Chinese Communist Party and government.

Police in the southwestern city of Chengdu said in a statement that Liu and another person detained alongside him had been released on "bail pending trial".

"The investigation in the case is ongoing," it said.

The statement referred to the two men only by their surnames. When their detention was announced on February 2, several Chinese media outlets, as well as rights group Reporters Without Borders, identified them as Liu and Wu Yingjiao, another journalist.

They were suspected of spreading "false accusations" and conducting "illegal business operations", according to the initial police statement in the case.

Liu and Wu had recently published an article online alleging corruption by Pu Fayou, the Communist Party secretary of Pujiang county in Sichuan province, and other county officials.

Liu was also arrested in 2013 for alleged defamation, although the charges were later dropped.

A screenshot of a text message conversation between Liu and someone claiming to be from the Chengdu Commission for Discipline Inspection -- a body that investigates corruption and misconduct allegations -- has circulated online since his latest detention.

The message reminded Liu to report complaints through legal channels.

China ranks 178th out of 180 countries in Reporters Without Borders' Press Freedom Index and is the world's largest jailer of journalists, according to the rights group.