Work to modernise old lifts at public housing estates almost always goes far too slowly, the Audit Commission complained on Wednesday.

It noted that the Housing Department has a target for lift upgrades to be completed within 7.5 months.

But the auditor looked at what actually happened regarding work on 238 lifts in recent years and found that only one was reopened for use within that time frame.

Almost 80 percent of the projects took between 7.5 months and 10.5 months, while work on 20 percent of the lifts took between 10.5 months and 14.5 months, the auditor said.

Even once work on a lift is finally completed, it can still take weeks for it to be re-opened.

The auditor said it compared the dates of the lift use permits issued by the authorities with the dates the lifts actually started moving again and found only 12 of the 238 lifts got going immediately.

More than 60 percent of the lifts were still not operating 10 days after their permit was issued, while more than 10 percent were still closed a whole month later.

The auditor urged the authorities to reduce the lift shut-down periods as far as possible in order to minimise disruption to the public, and to get the lifts going again as soon as they can once a permit is issued.

Director of Housing Rosanna Law agreed with the auditor's recommendations.

She said delays to lift modernisation work are mainly due to necessary final touch-ups, but the department will try to strike a balance between the scope of the work carried out and the shut-down period.