BEIJING (AFP) - A Chinese court has condemned a Hong Kong publisher who planned to release a dissident's book about President Xi Jinping to 10 years in jail, his lawyer said on Thursday.

Yao Wentian, 73, was given the sentence for smuggling on Wednesday by the Shenzhen Municipal Intermediate People's Court, one of his lawyers Ding Xikui told AFP.

Yao, also known as Yiu Man-tin in Cantonese, is the chief editor of Hong Kong's Morning Bell Press and has previously published politically sensitive books that were banned in mainland China.

He had been working with US-based author and dissident Yu Jie to release "Chinese Godfather Xi Jinping".

But Yao was detained last October after he was "lured" to Shenzhen, next to Hong Kong, previous media reports said.

Ding said Yao was convicted of smuggling a chemical raw material, with the court ruling that he had avoided tariffs of 740,000 yuan (S$148,200).

His lawyers argued he was only an accessory.

"The sentence was too heavy," Ding said, adding Yao has until May 17 to lodge an appeal.

Censored Chinese books have become a big seller in the former British colony of Hong Kong, a semi-autonomous region of China which enjoys a separate legal system.

In 2012, Yao complained to Google, saying his Gmail account had been hacked while he prepared to release Yu's "Hu Jintao: Harmony King", a book on China's former president.

China came 173rd in a press freedom ranking of 179 countries issued by the advocacy group Reporters Without Borders last year, climbing one place from the previous year.