"Seeking justice for a daughter is every mother's responsibility," Yu said. "Is this still a country if we just allow officials to abuse the rule of law?"

Yu has been compared to Tang Hui, a Hunan mother who gained national sympathy after she was sent to a labour camp while seeking justice for her daughter who was abducted, raped and forced into prostitution.

Yu has been warned a number of times by police, been detained three times and undergone re-education through labour for four months, but she is not about to give up.

"I must seek justice for my daughter even if I must pay the price with my life," she said.

The extreme lengths taken by some parents of sexual-abuse victims in the name of justice highlights a wider perception that the judicial system is failing to handle rape cases properly.

Legal experts say rectifying the problem requires in part addressing an egregious inconsistency in the Criminal Code on the meaning of "consent".

In 1997, legislators amended the code to introduce the crime of soliciting an under-age prostitute. There was already a law that defined sex with a girl under 14 as rape, and offenders could be sentenced to death.

The new solicitation charge carried the lesser punishment of five to 15 years in jail.

Legislators thought it unfair to charge a man with rape for hiring a prostitute who later turned out to be minor, as he might not have been aware of her age.

In addition, by becoming a prostitute, the girl had given some indication about consensual sex, they argued.

Legal experts have lobbied for years to have the "under-age prostitution" charge dropped, saying it allows powerful officials or connected businessmen to get away with light sentences for committing rape.

In June, the conducted an online poll and, although it did not say how many took part, found that more than 90 per cent of respondents supported abolishing the solicitation charge.

The renewed focus on the charge comes amid a string of highly publicised cases involving schoolgirls. Although there is no official public data on the national number of rape cases involving minors, China News Service reported recently more than 2,500 girls had been sexually assaulted in Guangdong over the past three years.

Last month, the Supreme People's Court, the Supreme People's Procuratorate and the ministries of Justice and Public Security published a detailed guideline listing seven circumstances in which sexual abuse of minors warranted "severe punishment". But the guidelines did not spell out what the more severe sentences should be.

Some lawyers said the announcement served little legal purpose and was more aimed at placating an angry public.

Wang Yu , a Beijing lawyer who represents parents of sexually abused children on a pro bono basis, said the guideline was meaningless.

"Nothing should override the nation's top criminal law, which states that all kinds of sex acts with girls who are under the age of 14 should be treated as rape. The guideline is muddling the criminal law," she said.

Wang said offenders who should be tried for rape were being charged with solicitation because of judicial corruption and the Communist Party's power over the courts.

"The charge of soliciting under-age prostitutes protects officials and tycoons from being charged with rape," she said.

"There are too many interests at stake for this charge to be abolished," Wang said.

She added that she did not expect any change in the law for at least the next five years.

Prominent rights lawyer Si Weijiang said the lack of full-time lawmakers in the National People's Congress meant amending the law was an extremely long procedure.

"Most National People's Congress members are serving on a part-time basis and only meet for four to five days a year," Si said.