A recent local newspaper report in Northeast China that warned it has become common for some college teachers to defame China in class has ignited heated public debate.

The report, in the form of an open letter to college social science teachers, discussed what is considered three major problems in today's college education system after assigning reporters to sit in 100 classes in over 20 universities in five cities, including Beijing, Shanghai, and Guangzhou.

The newspaper, Liaoning Daily, launched the investigation after receiving messages from students, who said that it appears fashionable for college teachers to speak ill of China and criticize its society.  The report added the students claim some teachers always compare China to other countries.

The letter claimed that many teachers always made inappropriate comparisons between the late Chairman Mao Zedong and emperors in ancient times.

Some of the teachers openly questioned major policies of the central government, believing China should pursue the Western model, the newspaper said.

They exaggerated problems like corruption and social inequality on the country's development path as defects in the political system, the letter said. 

"Please treat the country (China) you live in with more respect. You can point out China's problems, but have to make it clear and objective. Don't just slap and curse China at will," the newspaper said.

The letter's link spread quickly on Sina Weibo, China's Twitter-like service, and hundreds of comments were posted before they were reduced to just over 60 and were mainly positive responses.

Some college teachers reacted strongly to the newspaper's "investigation" and remarks.

"College classrooms should be places where ideas can be freely exchanged, where teachers and students openly discuss society," a professor of journalism who preferred not to be named told the Global Times Sunday.

"Shades of the Cultural Revolution (1966-1976)," said the professor, who believes teachers' lectures have been overly politicized.

However, some Net users supported the report, saying that "as a student, I want to hear more rational analysis and comments in class instead of endless ranting about social inequality. However, most teachers always blame setbacks in life to society."

"Universities allow different voices. However, defaming China and the Chinese nation is illegal. Other countries do not tolerate this," said Zhou Xiaoping, a well-known online commentator and writer.

John Ross, a senior fellow at the Chongyang Institute for Financial Studies of Renmin University of China, said that he agreed with the newspaper's stand.

"There are many Chinese lecturers who are patriots. As a foreigner, I often was shocked by some Chinese college teachers who defamed China," he told the Global Times.

The Chinese central government issued a guideline in October to strengthen teachers' ideology, stating that teachers should have correct values and bring core ideas of socialism to students and spread positive energy.