If the planned Occupy Central demonstration takes place and police make a high number of arrests, there will be room in the city's prisons for the detainees, according to Commissioner of Correctional Services Sin Yat-kin.
"We are confident that we can take care of more such people under our custody using our current resources," Sin said, adding that the prison population is at a 20-year low.
The Occupy Central non-violent civil disobedience movement plans to mobilise over 10,000 people to blockade streets in Central if the government fails to deliver a satisfactory proposal for political reform ahead of the 2017 chief executive election.
Last year, the average daily prison population dropped to 9,206 from 9,247 in 2012. The average occupancy rate was about 80 per cent.
With prisoner numbers slightly down, the department plans to revamp some older facilities which were not purposely built to be prisons. Fifteen of its 29 correctional facilities will have been in use for more than 40 years by 2019.
A partial redevelopment project is underway at the Tai Lam Centre for Women. It is expected to provide 108 additional prison places and make it better able to house female inmates that are a high security risk, Sin said.
The department has no plans to build any institutions at new locations, he added.
Some 109 inmates newly admitted to penal institutions last year were classified as high security risks because they were sentenced to imprisonment for 12 years or more. Another three new admissions were considered high-risk because of factors such as their conduct in custody or because they were key members of triad gangs.
Some 98 of the new high-security inmates had committed serious drug-related offences; 60 came from other countries.
The number of inmates who required medical treatment outside of correctional institutions also rose last year. Staff spent 39,700 days of work on medical-escort duties, a 10 per cent rise on last year.
The decision to transfer an inmate for medical treatment is made solely by government doctors stationed at each facility, Sin said. Inmates required external treatment for "acute illness or accidental injury", the department said, but no detailed breakdown was provided.
Last year at least 10 more officers were assigned to medical- escort duty than in 2012, Sin said, adding that the department would require further resources if the trend continued.
This year, the department plans to recruit at least 50 officers and 240 assistant officers to replace retiring staff.
Despite no prisoner escapes since the early 1980s, the department also spent HK$660,000 on a system for detecting prisoners hidden in vehicles leaving or entering its facilities.
The system, deployed since January, can detect a heartbeat inside a vehicle and has a 100 per cent success record in trials, according to the department.
Officers can complete a vehicle search in 60 seconds using the system, it added.
The department will consider purchasing additional systems after the trial period ends in June.