The Correctional Services Department (CSD) has condemned a former student activist for violating his supervision order as it issued a recall order for Tony Chung, who said he's now in Britain.

Chung, former convenor of the now-disbanded group Studentlocalism, was sentenced to more than three-and-a-half years in prison in 2021 on secession and money laundering charges. He was released in June this year and placed under a year of supervision by the CSD.

Chung travelled to Japan during the Christmas holiday, and deputy commissioner of correctional services Leung Kin-ip said on Friday he failed to return to Hong Kong this week as expected.

The former Studentlocalism convenor said on social media he is seeking political asylum in the UK.

"For his irresponsible behaviour, we really condemn it. He will face the result as we will recall him back to prison to serve the remaining sentence," Leung said.

The official added that a supervision order serves the purpose of preventing a person from committing the same offences.

"We mainly focus on the rehabilitation need of the individual supervisee. All supervisees are treated the same. There is no special restriction on people who violate the national security law or who have joined the protest or the social movement," he said.

"There's no such thing about violating the freedom of speech. But when we consider such behaviour that will likely make him being arrested and go back to prison, we must stop it and give him advice."

In Beijing, Foreign Ministry spokeswoman Mao Ning said Hong Kong is a society with the rule of law, and attempts to evade legal responsibility are “in vain”.