BEIJING (AP) -- Four Shanghai prison officials were sentenced up to 11 years in jail on bribery charges after giving preferential treatment to a jailed real estate tycoon, state media reported.

Zhou Zhengyi, once ranked as one of China's richest men, was sentenced June 1, 2004, to a three-year term for fraud and stock manipulation. While at Shanghai's Tilanqiao Prison, he was allegedly given access to an air-conditioned office and phone, and permitted up to nine visits per week when the usual maximum is one per month, the financial magazine Caijing has reported.

Zhou was also not required to work, and his identity at the prison was kept secret to avoid attracting attention, the magazine said.

The former director of Tilanqiao Prison, Huang Jian, was sentenced to 11 years after the court found he took 400,000 yuan (US$53,000; euro39,000) in bribes, in return for giving Zhou preferential treatment, the official Xinhua News Agency reported Friday, citing the Shanghai No. 2 People's Court.

Three other prison officials were given two-year sentences.

Also known as Chau Ching-ngai, Zhou made millions of dollars in restaurant and retail businesses before moving into property development. He received early release on May 26, 2006, with time served.

Zhou was arrested again in January on charges of bribery and using phony tax receipts amid a sweeping corruption probe.