An 80-year-old man surnamed Wu is sentenced to five years' imprisonment in 2008 by a local Chongqing court.

Easy meat

Younger girls make easier prey. With reform and opening-up, grandparents or other older relatives are increasingly drafted to look after the vulnerable children of migrants gone to work in the big cities.

Many victims don't go to the police, preferring to avoid the public stigma, the report pointed out. Parents in violation of the local one-child family planning policy most especially don't like to alert police, according to the Shanghai judge.

Rural parents fear fines of about 20,000 yuan ($2,976) while Beijing and Shanghai citizens face more than 100,000 yuan ($114,880) punishments, according to the National Population and Family Planning Commission of China.

"We can see most children left in villages are girls and a lot of them are not the only child of the family," he said.

"By traditional Chinese thinking, boys are always given more care, especially in remote areas and so parents always bring the boys with them to the city.

"That means the girls are easily targeted and those criminals know they are very likely to avoid being exposed."

Of the 59 criminals aged 60 to 81 at the Jiangsu Second Reformatory, 70 percent were rapists.

"The elderly of China have been through tough times in their life," said psychology expert Yan Wenhua of East China Normal University in Shanghai.

"Some experienced war. Most went through the Cultural Revolution as well as the economic boom when lots of Western ideology poured into China.

"People like them, well, their minds were somehow distorted.

"They maybe have been through more than three sets of value orientations in their life and so they too are victims."

A recent draft amendment to China's criminal law put forward at the December 20-25 11th National People's Congress Standing Committee meeting suggested lighter punishments for the over-75s, including no death penalty except for extremely cruel murders.

Its critics argued every adult should be treated equally under the law and age discrimination need not be codified.

"Crime cases related to senior citizens in reality already receive lighter punishments, even without a law stating it," Qin Xiyan, a delegate to the National People's Congress told the Beijng Legal Daily, "and I also agree the death penalty can be deleted from some specific crimes but for a specific group of people who are neither minors nor pregnant women, this is entirely inappropriate."

Extra fairness towards seniors is unfair on the victims, critics argued, and could lead to a refusal to cooperate with police and courts, not to mention petitioning.