BEIJING (AFP) - A legal expert at a top Chinese university has inflamed controversy over a gang-rape case by calling the act less harmful if the victim was a bar waitress.

Charges last week against Li Tianyi - the 17-year-old son of an army general - tapped into growing popular resentment at perceived privilege for elite families.

Li's family were reported as saying the alleged victim may have worked at the bar which the teenager and his friends were visiting - prompting law professor Yi Yanyou from the prestigious Tsinghua University in Beijing to step into the debate.

"Stressing the woman was a bar waitress is not to say that raping bar waitresses is OK, but that the likelihood that a bar waitress is willing to engage in sex is greater," he said on the popular Chinese microblog Sina Weibo.

"Even if it was rape, the harm of raping a bar waitress is less than raping a woman from a good family."

The post was not visible on his account on Wednesday, but media outlets shared images of it and Weibo users unleashed fury.

"How can an animal like this sneak into Tsinghua? What is going on with this country?" said one, calling Prof Yi's comment "ignorant".

Social critic and author Li Chengpeng likened his comment to saying it was less harmful for officials to beat street vendors than shopowners.

"A lot of people in China have this shameful logic," he said on Weibo.

A lawyer for the victim said in a statement that she rejected the Li family claims about her, and in any case no women should have to face sexual assault, the Beijing Times reported on Tuesday.

Li's father Li Shuangjiang holds the rank of general as dean of the music department for the army's academy of arts.

The teenager already came under public scrutiny in 2011 after he and a companion, both driving expensive cars, attacked a couple for blocking their path.

He was sent to a correctional facility for one year and the general apologised for his son's actions.

Public resentment has mounted towards the children of high-ranking officials and rich families seen as living extravagantly or above the law thanks to their connections.

In a prominent scandal the son of a police chief in 2010 tried to assert his father's status to avoid responsibility after he ran over a student.

"Sue me if you dare. My father is Li Gang!" he cried, in what became a catchphrase referring to privileged children. He was later sentenced to six years in prison.