The brother-in-law of China's jailed Nobel Peace Prize winner Liu Xiabao has gone on trial on fraud charges that his lawyers say amount to a trumped-up case aimed at punishing the family.

Liu Hui's trial opened Tuesday at a courthouse on the outskirts of Beijing. Defense lawyer Mo Shaoping says the case stems from a real estate dispute with a business associate that already has been resolved, and that the fraud charges are unwarranted.

Chinese authorities commonly put pressure on relatives and friends of government critics to keep them in line.

Once a literary critic, Liu Xiaobo had campaigned for peaceful democratic change for 20 years and been imprisoned three times before his current stint, an 11-year sentence for drafting a call for political reform called Charter '08.