The Productivity Commission numbers come as Premier Annastacia Palaszczuk pledges new laws designed to drive down youth crime will be a priority when parliament returns next month.

However, it has emerged that teenage offenders are spending weeks at a time locked up in police watchhouses because there is no room for them in the state’s youth detention centres.

Two teenage boys spent more than two weeks in the Mount Isa watchhouse this month after it was discovered that all three of Queensland’s three youth detention centres were full.

One of the boys, 15, spent 15 nights in the watchhouse after being charged with unlawful use of a motor vehicle and unlawfully taking a child under 16.

Police allege he and an accomplice stole a car on New Year’s Eve after it was left in a driveway with the engine running and a three-year-old child in the backseat. The pair allegedly drove the car around Mount Isa for 30 minutes before leaving the three-year-old on the side of the street and eventually dumping the car. He was granted bail last week.

Close to 57 per cent of Queenslanders aged 10 to 16 at the time of release returned to some form of sentence supervision within a year in 2019-20, the figures released on Tuesday show.

The rate is the highest among all jurisdictions , but continued a downward trend over the previous two years that peaked at 65 per cent in 2017-18.

Palaszczuk announced a plan targeting young offenders following the stabbing death of mother-of-two Emma Lovell during an alleged home invasion late last year.

The premier on Monday said new laws are currently being drafted and will be introduced when parliament returns in February.

“They need to have programs … to see that they will actually have work when they leave prison,” she said.

“Some of these young people have complex backgrounds, and … we need to help break that cycle of crime.”

The plan includes longer prison terms for car thieves, increased penalties for those who boast about crime on social media and judges will have to take the histories of child offenders into account when deciding on bail applications.

Mount Isa magistrate Eoin Mac Giolla Ri said the teen, who was on probation at the time, had a “substantial criminal history” including several burglary offences allegedly committed in September and October last year.

However, he granted the boy’s bail application, saying there was little chance of him being transferred to a detention centre and keeping him in the watchhouse was against police procedure.

“There are many sound reasons for this policy that I do not need to discuss in these reasons. It suffices to say that conditions in watchhouses are harsh and that adult detainees are often drunk, abusive, psychotic or suicidal,” he said in his decision.

“Although children may be kept in separate cells, those cells are usually open to the sights and sounds of the watchhouse. Equally, there is no facility to deliver education or the therapeutic interventions that are sometimes available in detention centres.”

He said there was another child in the Mount Isa watchhouse who had been there for 18 nights.

Mac Giolla Ri said that although the alleged offence was serious, the boy was not the driver of the stolen car and had shown he was capable of not offending for extended periods of time.