The Correctional Services Department (CSD) on Monday dismissed claims by activist Joshua Wong that one of its officers imposed corporal punishment on a national security suspect.
Wong said on his Facebook page on Sunday that he was told by a prison source that 19-year-old Tony Chung was ordered to undergo foot drill for more than four hours for two straight days.
Chung was remanded into custody last month after appearing in court charged with secession, money laundering and conspiracy to publish seditious material, pending his next court appearance in January.
Wong also posted the name and photo of the prison officer serving in Pik Uk Correctional Institution said to be involved.
In a statement, the CSD said its investigation found Wong's allegation to be untrue, describing it as "malicious".
"It is an attempt to undermine the confidence and the integrity of all correctional officers by smearing. It is not the first time that, failing to present any concrete evidence, the member of public concerned lodged malicious allegation against the correctional officer," a spokesman said.
The CSD added the matter had been referred to law enforcement agencies for follow-up action.
Back in May, the now-disbanded pro-democracy group Demosisto headed by Wong had also accused the same prison officer in Pik Uk of allegedly telling jailed demonstrators to slap themselves for singing the protest song "Glory to Hong Kong".