Premier Annastacia Palaszczuk announced the measure on Friday, following days of heavy criticism over its detention of children in maximum security cells built for adults, some for weeks at a time.

Bob Gee will step down as Deputy Commissioner of Police and State Disaster Coordinator after being appointed as director-general of the department, and will start in his new role on Monday.

He says he wants to get children out of watch house as soon as possible, but could not say when that would be achieved.

"Building more beds is an obvious answer, but it's not the only answer," he said.

"What I think we have to put into perspective, is that once those beds are built, there is a plan to do more than that.

"In the medium term, it is really about restorative justice principles, bringing together health, education, parents, community, to make sure that these children, who have complex problems, are supported."

This week, state parliament heard children were enduring lengthy periods in adult holding cells because the state's youth detention centres are full.

Some were held in isolation and some were held in suicide smocks.

Asked on Friday if she was comfortable no laws were broken in the management of children in police watch houses, Ms Palaszczuk said: "What I do know, is that I do not want young people in watch houses for any longer than is absolutely necessary."

Mr Gee has stressed his focus will be on preventative measures, and said he would work on a plan to solve poverty and disadvantage, particularly in the state's most rural and remote corners.

"What that requires is for all of us coming together and working on that problem," he added.

Former Police Commissioner Bob Atkinson, who reviewed the youth justice system last year, said court orders were governing the "circumstances we find ourselves in now".

"I'm sure that no one is comfortable at all with the current situation, but personally I can't see a way around it at the moment, and it'll probably only be able to be addressed over time," he added.

Both government staffing and funding allocated to the youth justice system will be redirected to form the new department, and there will be no changes to ministerial responsibilities.

The state government is spending $550 million to build new youth detention centres, expand existing facilities and on rehabilitation programs for young offenders.

Liberal National Party leader Deb Frecklington condemned the move, calling for a Royal Commission into the issues and more staff in youth detention.

Australian Associated Press