A fortune teller and close friend of China's disgraced former security czar Zhou Yongkang has been sentenced to seven years in prison for bribery and illegal land transfers, a court said Friday.

Zhou described businessman Cao Yongzheng, also a master of the Chinese meditation practice of "qigong", as "the most trusted person" in his circle, Chinese media reported previously.

At the time of Zhou's conviction and life sentence for bribery, abuse of power and other offences, the official Xinhua news agency said that he had passed five "top secret documents" to Cao, who testified against him.

Cao was convicted of bribery and illegally transferring and reselling land use rights and jailed for seven years, the Yichang Intermediate People's Court in the central province of Hubei said in a brief social media posting.

Cao owns oil companies and was "particularly familiar with Sichuan officials", the Southern Weekly reported in 2013, both areas power bases of Zhou's.

His business empire also encompassed property, entertainment and agriculture firms.

Zhou is the highest official to fall in the anti-graft campaign under President Xi Jinping, which critics say is open to being used for internal faction-fighting.