The university’s student union, which took down the poster as it was responsible for managing the wall at the Tai Po campus, said it did not support the message, but stopped short of condemning it.

The school is trying to track down the two responsible, but it is not clear if they are students or outsiders, as the wall can be accessed by the public.

Education University council chairman Frederick Ma Si-hang said: “I would like to ask everyone in

Hong Kong to answer one question: if they were parents, would they want their children to be educated by the two young persons?” The university is the city’s only tertiary institution dedicated to training teachers.

Ma promised a thorough investigation and disciplinary action against those responsible.

A teary-eyed university president, Stephen Cheung Yan-leung, said: “The people who put this message up showed no compassion; instead they chose to add insult to injury and rubbed salt into the wound.”

Education minister Kevin Yeung Yun-hung joined in the condemnation, warning that “moral and legal considerations” should also matter when exercising freedom of speech.

The university’s student union took a more muted stance.

“We do not support the statement, but we have to also respect that some people have these kinds of thoughts,” union president Lala Lai Hiu-ching said.

At the same time, the union also cautioned the university against taking any action to curtail freedom of speech.

“If any student is punished for making any ethically controversial remarks, we believe that students will become more afraid of expressing their own opinions ... and even indirectly lead to ‘white terror’ on campus.”

However, the chief executive insisted that freedom of speech and university autonomy were no excuse for spreading fallacies as she also condemned pro-independence banners and posters on campuses.

Despite the outrage, internet users continued to taunt Choi online, although many more also came to her defence.

The former secondary school principal’s appointment as the city’s No 2 education official in July was widely opposed by many critics who were suspicious of her pro-Beijing credentials and worried she would be instrumental in introducing national education to the school curriculum.

Civic Passion lawmaker Cheng Chung-tai took a shot at Choi on his Facebook page while commenting on recent suicides at the start of the academic new year.

“It is deeply saddening and regretful. Officials in the Education Bureau, today you’ve finally understood the brutality of the education system when karma fell on you.” he wrote. “Don’t blame the crowd for being insensitive, because this karma is what you planted by yourselves.”

Additional reporting by Shirley Zhao