The Chinese University of Hong Kong has warned student union candidates against engaging in activities on campus that break the law or jeopardise national security.

The university was responding on Wednesday to claims by the candidates, who are running for the union cabinet, that management had joined with police to have students arrested following an attack on security guards, in which an unknown white powder was hurled at them. Students have accused the guards of abusing their power in the past and treating them as the “enemy”.

The scene on campus after an unknown white powder was hurled at security guards last month.

The candidates have published an 80-page manifesto stating the national security law infringes upon basic human rights and freedoms and is a disgrace to residents’ dignity.

In a recent media interview, they also vowed to maintain the “local and radical” ideology of their predecessors to “build localism and consolidate the identity of Hongkongers”.

Those words appeared to alarm management, which said it would not tolerate unfounded accusations or any possibly unlawful remarks.

“It is necessary and a duty for the security guards to turn to law enforcers amid illegal acts in campus,” it said. “Accusing them of abusing power is totally groundless.”

It added: “Having the proposed cabinet members participate and support non-cooperative movements to undermine the campus security policy is totally against the principle of a student union, which should safeguard the campus order and students’ welfare.”

The university would handle any illegal acts on its grounds seriously and cooperate with police to ensure no one was put at risk, it said.

Hong Kong’s student unions are known to be vocal on social and political issues, and have played an active role in movements such as the 2019 anti-government protests.

The union at Chinese University is in the process of selecting its cabinet, which includes the positions of president, external or internal vice-presidents and secretary.

Acting on a report by management, police last month arrested five students for their suspected involvement in the attack on security guards at the university’s Sha Tin campus.

The force believes the assailants sought to challenge a university policy requiring security guards to carry out identity checks at campus entrances.

Meanwhile, about 60 students at the University of Hong Kong attended a controversial screening on campus of the documentary Lost in the Fumes, about jailed pro-independence activist Edward Leung Tin-kei, to mark the fifth anniversary of the Mong Kok riot.

The university had earlier warned that showing the film could be a breach of the law and the social-distancing rule limiting public gatherings, but it did not intervene in the screening, which was held in the student union building.

About 60 students attended the screening of Lost in the Fumes at the student union building on Wednesday.

Tracy Cheng, vice-president of the student union that organised the screening, said: “It is an academic event. There is no political agenda. We think that the film is an objective account of what took place in 2016. It is important for Hong Kong people and young people to know the history of the city.”

She urged the university to respect academic freedom.

Among the attendees was a second-year faculty of art student, who declined to be named. “I don’t understand why the university has to make a fuss over it,” she said. “It is just a film. Does the university think we will become separatists after watching the film?”

While the university did not spell out what law it was referring to, the union accused the management of political suppression and claimed it had referred to the national security law in a separate informal document given to the student body.

Leung, an HKU alumnus, was a key activist in the 2016 Mong Kok riot and rose to prominence while running in the 2016 Legislative Council elections but was subsequently banned from taking part for advocating Hong Kong independence. He was jailed in 2018 for six years for his role in the riot.

The civil unrest, which erupted on the first day of Lunar New Year in 2016, saw some 91 people between the ages of 14 and 70 arrested over rioting, taking part in an unlawful assembly, assaulting police officers and other offences.

Two more screenings of the documentary are planned for Friday and Monday.