Chiu Kin-yip, a senior inspector of the police cyber security and technology crime bureau, said the arrest was related “to the recent incident about the returning officer’s decision to disqualify a number of candidates” who sought to run for Legco. “The suspect had posted some political views online,” he said. “We would rather not reveal the political background of the suspect.”

Police took him from his home in Yiu Tung Estate in Shau Kei Wan to police headquarters in Wan Chai for questioning on Wednesday. They also seized two mobile phones and a tablet.

Chiu added that the man was arrested for being suspected of “obtaining access to a computer with an intent to commit an offence or with dishonest intent”.

He stressed that police had acted on complaints and that the arrest had nothing to do with the suspect’s political background.

“Getting prepared to die for revolution?” he wrote.

The news of Chan’s disqualification sparked “digital bullying”, with returning officer Alan Lo Ying-ki’s personal data being exposed and circulated online. Some users called on the public to recognise that the civil servant had given up his “political neutrality”.

Chan’s party had tried to distance itself from the bullying and said it would not encourage such acts, although it said it appreciated people’s anger.

Another candidate, Nakade Hitsujiko of Nationalist Hong Kong, was also disqualified.

A police investigation was still ongoing, and the force said it would not rule out arresting others.

Chiu noted that the force respected people’s right to express their views but warned that statements posted in cyberspace would be subject to the law.