BEIJING (AFP) - A Chinese mother sent to a labour camp after demanding the men who kidnapped and raped her daughter be punished appealed on Tuesday against the dismissal of her lawsuit for compensation, a court said.

The sentencing of Tang Hui in August last year sparked public outrage, prompting her release just a week into her 18-month term, and unleashing criticism of China's "re-education through labour" system.

She sued for compensation earlier this year and lost the case, but later filed an appeal.

"The hearing has begun," the Hunan provincial high court in central China said on its official account on Sina Weibo, a Chinese version of Twitter.

More than 200 people including 50 journalists were attending, it said in a series of Weibo posts accompanied by photos in and around the courtroom.

In 2006, Ms Tang's daughter, 11 at the time, was kidnapped, raped and forced into prostitution, prompting Ms Tang to seek justice for the abductors and the police she says protected them.

She took dramatic steps such as kneeling outside the Hunan high court and travelling to Beijing to file petitions with higher authorities, an age-old practice in China that irritates local-level officials.

Seven men were finally convicted in June 2012, with two condemned to death, four given life sentences and one jailed for 15 years.

But Ms Tang continued to agitate the policemen to face trial, and two months later she received her labour sentence, accused of "seriously disturbing social order and exerting a negative impact on society", the state news agency Xinhua reported.

After her release she sued for 1,463.85 yuan (S$300) in compensation for the time served. The lawsuit was rejected in April.

China's re-education through labour system gives police the right to hand out sentences of up to four years without a judicial trial.