Image caption Liu Xiaobo received the Nobel Peace Prize in 2010

The brother-in-law of jailed Chinese Nobel laureate Liu Xiaobo is being held on fraud charges, his lawyer says.

Liu Hui was detained in January over a property dispute, his lawyer Mo Shaoping said, adding that the evidence against him was "insufficient".

Liu Xiaobo was sentenced in 2009 for helping to draft a manifesto - Charter 08 - calling for political change.

His wife, Liu Xia, has been under house arrest ever since he was awarded the Nobel prize two-and-half years ago.

Confined to her Beijing apartment with no internet or phone access, and limited to weekly visits to family members, she has described her house arrest as a painful experience.

Liu Xiaobo is currently serving 11 years in jail for inciting the subversion of state power. He won the Nobel Peace Prize in 2010 despite the Chinese government's fierce opposition.

"[Liu Hui] should face trial soon, within a month," Mo Shaoping told the AFP news agency.

He could not confirm whether the charges were connected with the activities of his brother-in-law, but said he had been under constant "surveillance by public security units" in recent months, AFP reports.

Some 134 Nobel laureates and Chinese activists wrote to Xi Jinping, the new head of the Communist Party, in December asking for Liu Xiaobo's release.