China's economics students are being "brainwashed by Western theories" and need to read more Marx, Chinese professors said in a letter to the education ministry, amid a widening crackdown on foreign ideas.

As the world's number two economy faces a slowdown and struggles to adopt much-needed reforms, economics students at Chinese universities should study a curriculum composed of at least half Marxist courses, said the petition, otherwise they will become the "grave diggers of the socialist economic system".

It is the latest effort by China's ruling Communist party to push its ideology in classrooms as President Xi Jinping, who has overseen tightened media censorship and a crackdown on dissent, has called for the Communist party to increase control over universities.

"It is in essence an ideological class struggle wherein the bourgeois class clashes with the proletariat class in education," the letter's co-author told the state-run Global Times Tuesday, adding that the letter had dozens of scholars supporting it.

"How can a socialist university be allowed to educate such people who will become the grave diggers of the socialist economic system?"

The petition did not address whether Marx, a German-born political theorist, revolutionary and philosopher who spent much of his life in England, should be considered "Western".

Schools have become an ideological battleground for the ruling party, with the country's education minister saying in 2015 that textbooks promoting so-called "Western values" should be banned.

Internet users have fiercely debated new revisions to China's primary and secondary school textbooks that state media criticised for paying too little attention to the Communist Party's revolutionary heritage and patriotic content.

Replaced textbook contents included a passage inviting readers to imagine the experience of being an intercontinental ballistic missile and the tale of man punishing a "rich hooligan" by beating him to death, the Global Times reported.

Although officially socialist in name, China has since the late 1970s embraced capitalism and experienced surging growth as the role of the state diminished and market forces fuelled a transformation of the economy.