Prison officials have defended their decision to refuse to allow Wu Chi-wai to attend his father's funeral by saying they have to ensure the safety of their officers, the public and Wu himself.

In a statement, they said various factors had been taken into account in denying permission for the former Democratic Party chairman to go to the funeral this Friday, including the "offence(s) committed by the subject person in custody (PIC), security risk, escort route, location safety, etc".

The Correctional Services Department (CSD) said its statement on Wednesday was issued in response to an Apple Daily report and "criticism that the decision was not sympathetic and made out of political suppression".

"It was noted that the date, time and location of the funeral have been extensively reported on social media platforms recently, and there were calls on the internet for showing support at the scene on the day of the funeral," it said.

"After a risk assessment, the CSD has decided to reject the application in order to protect the safety of correctional officers, the subject PIC and members of the public."

The department said it offered its deepest condolences to Wu and if he so wishes, he can follow the funeral proceedings via a video streaming platform.

Wu, who faces various protest-related charges and an alleged national security offence, was first taken into custody after a court heard that he had failed to surrender a BN(O) passport while on bail. The government no longer recognises BN(O) passports as valid travel documents.