A Chinese court on Wednesday jailed a billionaire farming tycoon for 18 years on charges of "provoking trouble" after a two-week trial shrouded in secrecy.

Judges in Gaobeidian near Beijing said Sun Dawu was found guilty behind closed doors of a range of crimes, handing him a fine of 3.11 million yuan ($480,000, €406,000) in addition to the custodial sentence.

They included "gathering a crowd to attack state organs, obstructing government administration, and picking quarrels and provoking trouble."

The latter charge is a catch-all term often used by Chinese authorities against dissidents.

Why was the farming tycoon arrested?

Police arrested Sun in November along with as many as 20 relatives and business partners.

The arrests came as his firm became embroiled in a land dispute with a state-owned rival.

Sun built up his Dawu Agricultural and Pastoral Group into a multi-million dollar business over the past three decades.

The 67-year-old started the company with his wife with just a few chickens and pigs in the 1980s.

It employed over 9,000 people before Sun's assets were seized by the state and employees forced out of work after his detention.

What issues did Sun speak out on?

The entrepreneur has long been a vocal critic of the Chinese government and its rural policies, demanding less state interference in the running of farms.

He also took aim at Beijing over its handling of a swine fever outbreak in 2019, accusing local authorities of trying to cover up the scale of the outbreak.

A three-year suspended jail term in 2002 for illegally taking public funds was eventually overturned after an outcry from human rights activists.

Sun's lawyers shared video footage that showed him surrounded by security guards and plain clothes police officers.

His legal team said prosecutors told the court that his activities had "endangered national grassroots stability."

Sun said during the trial that he had gone on hunger strike in protest at his treatment whilst in detention.

China has moved to crack down on a number of high-profile business executives in recent years over their criticism of the government.

Ren Zhiqiang, a property developer, was also handed an 18-year jail term after he wrote an article slamming President Xi Jinping's handling of the coronavirus pandemic.

jf/jsi (AP, AFP)