BEIJING, Dec. 4 -- A seasoned Chinese doctor recently helped expose the practice of patients sneaking red envelopes filled with money into Chinese hospitals for better treatment.

Dr. Li Rui, however, was not discouraging the practice when revealing 'gray income' to a classroom of med students. Quite the opposite.

The Beijing doctor, working at the Aviation and Space Center Hospital affiliated to Peking University and a teacher with the famous New Oriental School, told a group of students that "you should definitely take 'gray income' sent in by patients when it's necessary."

"If you help 100 patients remove their kidney stones in one night, you can expect to buy a Porsche overnight," Li said as he delivered a lecture, which was caught on tape and posted on microblog Sina Weibo this week.

In the video footage, he also said doctors can fabricate medical journals however they wish.

In a country with increasing violence stemming from strained doctor-patient relations, Li's remarks only fanned anger, with the public lashing out at the doctor with a spasm of scathing comments.

"Such doctors should be sacked," wrote a Weibo user.

"Face it, this is reality in China's medical industry," read another comment.

One person advised people to avoid "expensive nightmares" as much as possible.

On Wednesday, Li issued a public apology for what he said. His employer New Oriental apparently caught wind of the incident and ended his contract. Videos of his previous lectures have been removed from its website, the school said on its official Weibo account. The hospital he worked with has launched an internal investigation into the case.

In China, some patients, including expecting mothers, are believed to surreptitiously deliver extra money sealed in red envelops, or "hongbao," to doctors to make sure their operations go smoothly. Li's comments are seen as a proof of this practice.

The hospital firmly dismissed the lecturer, saying on their official website that Li's comments are far from the truth and a defamation to medical staff.

But those in the sector argue differently.

A doctor surnamed Wang with the oncology department of a hospital in Henan Province told Xinhua that taking additional money is "industry routine."

"Sometimes we get the 'red envelops' from patients as well, because they want the best doctor or to book the earliest operation date," Wang said.

But doctors are increasingly careful in accepting money these days, out of concerns about media exposure. Now, they only take the money from acquaintances.

Liu Yong, a resident of Henan's Xuchang City, said he prepared a "hongbao" for surgeons so his father's operation in a Zhengzhou hospital would proceed as soon as possible. But his offer was refused because he didn't know any hospital staff.

As outrage and concern run high, many are demanding the practice be dealt with.

Shi Pu, a professor with Henan University of Economics and Law, said the only way to avoid such phenomenon is to better supervision.

"Stricter punishment should be meted out to doctors who take 'hongbao' and authorities should stick with that rule," Shi said.