BEIJING — Students and professors in China denounced a leading university on Tuesday for trying to silence activism about sexual harassment, a rare act of defiance that is testing the limits of the country’s fledgling #MeToo movement.

The institution, Peking University in Beijing, remains in an uproar after a student activist said that an instructor accompanied by the student’s mother had visited her dormitory at 1 a.m. Monday to warn her against continuing to speak out about a 20-year-old rape case that had embarrassed the university.

In a letter that was widely shared online, the activist, Yue Xin, said that the university had frightened her mother so much that she had threatened to kill herself.

The backlash against the university was swift and fierce. In an unusually bold move, a group of students posted banners accusing the institution of betraying its values, saying that Ms. Yue was upholding the spirit of the May 4 movement of 1919, a patriotic uprising led by students.