A Chinese court on Monday upheld lengthy jail sentences given to three anti-corruption activists, their lawyer said, cementing a crackdown on a burgeoning civil rights movement.

Liu Ping, Wei Zhongping and Li Sihua were charged with disrupting public order last year for taking photos of themselves holding banners which urged government officials to disclose their assets to curb corruption.

Under President Xi Jinping, China's ruling Communist Party has repeatedly vowed to combat rampant graft in the face of public anger over the issue.

But the party has cracked down on activists pursuing the same goals, seeing independently-organised groups as a challenge to its tight grip on power.

An intermediate court in Xinyu, in the central province of Jiangxi, upheld the six-and-a-half-year jail sentences handed to Liu and Wei, and a three-year sentence given to Li, their lawyer Si Weijiang told AFP.

China this year has jailed around 10 members of the New Citizens Movement, a loose network whose members held peaceful protests in Beijing and other cities last year calling for officials to disclose their assets.

At its peak the group had an estimated several hundred regular participants, who organised dinner discussions across China and pushed for legal and educational reforms.

A founder of the movement, legal scholar Xu Zhiyong, was jailed for four years in January.

New Citizens Movement members have said the wave of arrests, which began last year, has severely curbed their activities.

The jail terms passed in June on Wei and Liu, a 50-year-old retired steelworker, were the heaviest given to any of the movement's members.

Appeals in China's Communist-controlled court system are rarely successful.

"It's clear they have not committed a crime, and appealing was pointless, but Liu wanted to appeal anyway," lawyer Si Weijiang said.