Substantiated misconduct allegations against staff at Queensland's two youth detention centres have more than tripled in the past year.

The allegations verified by the Ethical Standards Unit include staff failing in their duty of care, excessive use of force and breaches of professional boundaries.

In the 2014-15 financial year there were 22 substantiated allegations but the number blew out to 76 in 2015-2016.

Despite that increase, only five staff and one contractor were sacked last year.

Six staff were fired in the previous year.

Shadow attorney-general Ian Walker said he was appalled.

"That is a huge number of allegations substantiated and a huge increase on the previous year," he said.

"That's a 350 per cent increase and you've got to say that's a worrying increase in anyone's language."

Complaints and substantiated allegations 2014-2015 2015-2016 Complaints 34 (against 49 staff) 83 (against 188 staff) Allegations 75 159 Substantiated allegations 22 (from 13 complaints) 76 (from 38 complaints) Sacked 6 staff 5 staff, 1 contractor

Mr Walker has called on the Government to investigate what had lead to the spike.

He suggested widening a current review into practices at Queensland's youth detention centres to address the recent data.

"We don't think that the current investigation, the current terms of reference, cover these serious matters," he said.

"I think Queenslanders have got every right to be concerned about how the Attorney-General is running Queensland's Youth Detention Centres."

"We'll be asking further questions because this data raises more questions than it solves. Exactly what are these allegations and how serious are they?"

A spokeswoman for Acting Attorney-General Dr Anthony Lynham said the number of complaints made against staff at youth detention centres varied year-to-year.

"In all years, the number of complaints substantiated was less than half of the total complaints," she said.

"The safety and security of young people and staff at youth detention centres is paramount, and this is why the Queensland Government encourages people to come forward with complaints, which are then thoroughly investigated."

Queensland has two youth detention centres — the Cleveland Youth Detention Centre in Townsville and the Brisbane Youth Detention Centre at Wacol.

The ABC has previously revealed some of the allegations at the Townsville centre.