Hong Kong’s police associations on Wednesday slammed the head of Chinese University for his “biased” statement that spelt out the alleged assaults and mistreatments some students claimed to have faced upon arrest for taking part in anti-government protests.

But the university’s students have extended their support for the vice-chancellor, Rocky Tuan Sung-chi, by writing hundreds of messages on a giant banner that was passed to the school management.

Last week, Tuan issued a statement that said “any proven case of improper use of force or violation of human rights by certain police officers must be condemned”.

He also wrote that the university had contacted more than 30 student protesters, some of whom said they were not given a timely access to lawyers, were slapped in their faces, and were forced to strip naked.

He has also pledged to support Sonia Ng, a student who claimed in a town hall-style meeting with Tuan that she was the subject of sexual violence by police.

In response, all four police associations on Wednesday criticised Tuan for not casting any doubts on the students’ claims.

“[You] have said nothing about the serious crimes the arrested students were suspected of committing,” said the statement by the Superintendents’ Association, the Police Inspectors’ Association, the Overseas Inspectors’ Association and the Junior Police Officers’ Association.

“Instead, even without evidence to back up those claims, you shouted at the top of your lungs that the police officers suspected of violating rules need to be probed and condemned.”

The associations also expressed regret that Tuan, as a scientist, had “neglected the principle of seeking truths”.

They asked Tuan if he cared to find out whether any of his students had taken part in riots or done anything illegal. If Tuan had done so, the associations said, he should ask the students to be responsible for their mistakes.

On Tuan’s remark that independent investigations “outside the existing mechanism” should be initiated to probe allegations made by his students, the associations said that would be tantamount to the “rule of man” and not the “rule of law” if everyone made such requests.

The university did not comment on the matter on Wednesday.

On the campus, the students’ union organised a campaign to invite pupils to write messages of support for Tuan on a giant banner that bore the words “conscience won’t be silenced in [the] face of authoritarianism”.

“Thank you for standing up for us,” one message read. Another read: “Thank you for taking the step. I hope we can walk together on this.”

Separately, in a statement late on Tuesday night, the students’ unions of Hong Kong’s tertiary institutions condemned the statement issued by the heads of eight university councils.

The council heads’ statement said universities were not battlegrounds for the resolution of political issues and should not be drawn into supporting any particular political position.

In response, the students’ unions said: “In such difficult times, leaders of the institutions should stand with the students and try to understand the reasons behind their actions, providing them with the support they need.”

The unions also said the councils should not stand with the “tyrannical regime in oppressing the citizens”.

“To punish the students and the members of the staff in the name of order and stability will only further push the youngsters of our city into absolute despair,” they said.

In Hong Kong, the chairmen of the university governing councils are appointed by the city’s leader. The student unions thus called them “puppets” and “marionettes”.

“The student unions urge them to stop their uninvited and unwelcome involvement in university affairs,” they added.