Queensland's Health Minister has ordered an investigation into why a toddler who died from traumatic injuries had earlier been allowed home from hospital with his family.

Cameron Dick said initial advice showed the clinicians fulfilled their duties to report Mason Jet Lee to the child safety department before his release.

His body was found at the home of his mother's partner at Caboolture, north of Brisbane, on June 11.

It is believed the 21-month-old's injuries were inflicted some time before his death.

"Initial advice is that we fulfilled our duties and responsibilities," Mr Dick said.

"We have done what we needed to do."

But he said: "Lets look at all parts of the system to see what has occurred and what we can do to learn from this."

Child Safety Minister Shannon Fentiman said a separate, independent investigation had already been launched - as is the case with all children who die who are known to her department.

It will examine why Mason was released to his family, despite the warning from doctors.

"Any recommendation will be implemented," she said.

"It is an absolute tragedy."

Queensland 'taking too long to address child safety notifications'

Opposition child safety spokeswoman Ros Bates fears the child safety department is haemorrhaging under pressure, and there will be another similar death.

"The fact that Mason was returned to his family is horrendous," she said.

"There is another Mason out there.

"The Minister needs to explain what they did, what they knew and what they will do so this never happens again."

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A Right To Information request secured by the Opposition showed 46 per cent of children who are reported to the department do not get seen within the 30-day timelines.

Ms Fentiman said Queensland's reporting system was more stringent than other states, as it is the only one that reports every child safety notification.

The Caboolture office received extra staff this year, and another 17 are to be employed across the state this year.

Ms Fentiman said the department was amid its biggest overhaul, enacting 121 recommendations from the Carmody report.

"I know we have a lot of work to do, we are three years into a 10-year reform."

Foster Care Queensland director Bryan Smith said "anecdotally we haven't heard that [child protection officers] are swamped".

However, he said the foster care system was straining to take in kids from abusive situations.

"We have 5,200 carers across the state and 9,000 kids in care," he said.

"There are more children coming into care this year, and the year before that."

Queensland police are treating Mason's death as a homicide and want to speak to anyone who had contact with Mason before his death.

The partner of Mason's mother was questioned by police for 18 hours but released without charge.