A prominent Chinese billionaire has been sentenced to 18 years in prison, the latest in a string of punishments against outspoken corporate bosses.

Sun Dawu runs one of the country's largest private agricultural businesses in the northern province of Hebei.

Sun, 67, has in the past spoken out about human rights and politically sensitive topics.

He was found guilty of "picking quarrels and provoking trouble" - a charge often used against activists.

Other charges against him include illegally occupying farmland, assembling a crowd to attack state agencies and obstructing government workers from performing their duties. He was also fined 3.11 million yuan ($478,697; £343,227).

Sun's company is among China's biggest, with businesses ranging from meat processing and pet food to schools and hospitals.