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 hostess.

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 Yi Yanyou, a law professor at the prestigious Tsinghua University in Beijing, to step into the debate.

"Stressing the woman was a bar hostess is not to say that raping bar hostesses is okay, but that the likelihood that a bar hostess 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 hostess 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 many Weibo users vented their fury.

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

Social critic and author Li Chengpeng likened Yi's comment to saying it was less harmful for officials to beat street vendors than shop owners.

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

Yi posted a brief apology on Wednesday evening, saying his comment was "not really appropriate" and had had a "negative impact".

A lawyer for the victim said in a statement she rejected the Li family claims about her and that no woman should face sexual assault, the Beijing Times reported.

"Just because some girls have had a drink with others, we cannot look at them with prejudice or carelessly infringe on their... right not to be sexually violated without any guilt or shame or legal responsibility," the statement said.

Bar hostesses in China are typically employed to drink with customers and the job has a reputation of potentially involving sex.

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 previously 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.