Both major parties in Queensland have failed Indigenous youth, a Greens MP says, with data showing an increase in serious offending rates after spending time in custody.

Youth Justice Minister Laura Gerber revealed a 21 per cent increase in serious offending for youths in the 12 months after being housed at Cleveland Youth Detention Centre (YDC) in Townsville.

The data, revealed in response to a question on notice by Greens MP Michael Berkman, also showed a vast discrepancy between the decrease in offending for young Indigenous people who have spent time in custody, compared to their non-Indigenous counterparts.

There was only a 2 per cent decrease in serious offending for Aboriginal and Torres Strait Islander young people after their release from detention, compared to 54 per cent for non-Indigenous children.

Mr Berkman said the data proved what experts have long noted—"detention does not work, especially for First Nations children".

"Right now, Cleveland is seriously understaffed and overcrowded. This means children are locked in their cells for long periods, and crucial rehabilitative programs cannot be delivered," he said.

"The results of the Labor and LNP's catastrophic failures at Cleveland YDC are clear."

His comments mirror those from Gunggari human rights campaigner, Maggie Munn last year, who noted: "More than thirty years since the Royal Commission into Aboriginal Deaths in Custody, countless inquiries and reports later, it's shameful that governments not only fail to listen to the evidence but go against it."

The revelations come after the new Queensland Government enacted a series of "adult crime, adult time" laws, which apply to children as young as 10.

13 offences will be designated as "adult crimes", including serious assaults, breaking, and entering, and dangerous operation of a vehicle, and if convicted, children are subject to the same custodial sentence as adults.

If convicted of murder, a life sentence with a 20-year minimum non-parole period must be enacted.

Last year, a report highlighted the death of two disabled Indigenous children who died in the aftermath of spending more than 600 days combined in separation—he government's term of solitary confinement.

The children had a history of exposure to extensive sexual and violent trauma, substance abuse, loss of culture, and likely had suffered from undiagnosed foetal alcohol syndrome.

When the LNP introduced their new legislation last year, they acknowledged they were discriminatory towards young people, and would "have a greater impact on Aboriginal and Torres Strait Islander children".

This, despite 45 per cent of all Indigenous children incarcerated on any given day across the country being in Queensland.

The government also removed the principle of detention of children as a last resort—a basic tenet of international conventions Australia has ratified, and of the Royal Commission into Aboriginal Deaths in Custody.

It led to NATSILS' chair, Karly Warner to argue Premier David Crisafulli was guaranteeing Indigenous children would be incarcerated more, and for longer.

"Locking children up deprives them of access to effective rehabilitation and entrenches them in perpetual cycles of trauma, violence and government neglect that led us here in the first place," she said last year.

Mr Berkman said children in detention were "not learning new skills, building positive social networks or getting any support for the factors that led them to offend in the first place".

"They leave having learned little other than how to offend more seriously."

Mirroring Ms Warner's comments last year, where she argued instead of trying to look 'tough,' governments had a responsibility to ensure they were reducing crime, the Greens MP - one of only two politicians to vote against the new 'adult crime, adult time' laws - said there was an "obvious" solution" available to the state government.

"Take the hundreds of millions of taxpayer dollars currently set aside for new youth prisons and spend it on the programs that actually work," he said.

"Fund youth services to stay open longer, support First Nations-led initiatives, and open more youth rehabs. Give kids a free breakfast at school, build more youth activity centres in our suburbs, and expand screening for FASD [Fetal Alcohol Spectrum Disorder] and learning disabilities."