SHENZHEN, China (Reuters) - Two Chinese students were assaulted and hauled away, according to a witness and video footage, after they led protests against their university on Thursday for refusing to recognize an on-campus Marxist student society.

The attacks came days after Ivy League Cornell University pulled the plug on cooperation with Renmin University in Beijing after students, also affiliated with their on-campus Marxist society, were punished for supporting labor rights in China.

Despite espousing Marxism as one of its leading ideologies, China’s ruling Communist Party opposes any form of activism or organization that has the potential to slip beyond its control.

Several Marxist university societies struggled to re-register this year on campus, students say, and activists believe authorities are worried about students using the groups for social activism.

Yang Kai and Zhu Shunqing, both members of the unofficial student Marxist group at Nanjing University, were among the leaders of protests on campus which drew a crowd of more than 100 people, according to video footage.

Yang, a fourth-year software engineering major at Nanjing in eastern China, was shoved and dragged on the ground before being bundled away by unidentified men, according to a classmate and fellow member of Nanjing’s Marxist student society who requested anonymity.

He spent just over four hours in police detention, the person said.

Zhu was assaulted by plainclothes police on campus on Thursday, said the student. On Friday, Zhu was grabbed, cursed at and forcibly taken from campus by relatives as university administrators looked on. Zhu’s current whereabouts were unknown, the classmate said.

Chinese authorities have been known to pressure relatives of students involved in demonstrations or social activism to get them to stop, students say.

“Today at midday as Zhu Shunqing was being kidnapped by his relatives, the heads of both the student welfare department and the media and communications department just stood by and watched,” said the classmate.

“They didn’t do anything to stop his relatives from pushing and shoving him and taking him away.”

Neither Zhu nor Yang could be reached for comment. Nanjing’s on-campus security department released a notice late on Thursday on the student portal stating the university had reported the protests to the police. The police station in Nanjing refused to comment by phone.

Around 50 students from across China including students from both Nanjing and Renmin went to southern China in August to protest against the treatment of factory workers.

In late August, police in riot gear stormed an apartment in Huizhou where the students were staying while they supported factory workers at Jasic International seeking to form a union.