HONG KONG (REUTERS) - A Chinese court on Friday (July 7) jailed a labour activist for 4.5 years following more than two years in detention on a subversion charge over a published account of the Tiananmen crackdown on pro-democracy protesters in 1989.

Police in the southern city of Guangzhou first detained Liu Shaoming in May 2015, and he was arrested soon after on a charge of "inciting subversion of state power", said a Hong Kong-based advocacy group, the Network of Chinese Human Rights Defenders.

Liu will appeal against Friday's decision by Guangzhou's Intermediate Court, his lawyer Wu Kuiming told Reuters by telephone.

"He's already been detained for two years... the sentence is too heavy," Mr Wu said. "He is innocent... he hasn't committed any crime."

Liu's son and wife were in court when the decision was handed down, his lawyer added.

Mr Wu said Liu spoke briefly in the courtroom, maintaining his innocence and saying the authorities had misinterpreted his writings on the overseas democracy movement and his involvement in the Tiananmen protests of 1989 in Beijing.

Liu had shared these writings over various social media and online channels in 2014 and 2015, rights groups said.

Telephone calls to the court in Guangzhou went unanswered.

Western countries have expressed repeated concerns about a widening campaign under President Xi Jinping to quash dissent among activists, rights lawyers, journalists, academics and others.

"All that Liu Shaoming is guilty of is the legitimate exercise of his freedom of expression," said Mr William Nee, a China researcher at rights group Amnesty International. "He is a prisoner of conscience and must be immediately and unconditionally released."

Liu had campaigned through the years on issues such as labour rights, besides helping to found "Labour Defence Volunteers", a group to assist blue-collar workers in southern China, rights groups said.