In his annual report to Parliament, DPP Daryl Coates SC warns that unless he is "given significant extra resources, the criminal backlog will continue to increase".

"The effects of such a large backlog has a deleterious effect on both the overall quality of justice and on individuals who come in contact with the justice system, victims, witnesses and accused alike," Mr Coates wrote.

"As cases become older witnesses' recollections are not as good and this can lead to a higher number of acquittals and discharges.

"Victims who have been highly traumatised are having to wait significantly longer for their cases to be finalised, often having to relive the trauma years after the event.

Mr Coates outlined a big increase in workloads with a 50 per cent increase in the number of committal hearings in the past two years "leading to a spiralling in the criminal backlog".

"The backlog has, in fact, increased from 382 in 2016-17 to 627 in 2018-19, an increase of 60 per cent," he said.

"Bail applications have increased by 400 per cent in the past four years. Sexual assault and family violence referrals have increased 250 per cent in the past six years and child safety matters have increased significantly since last year."

Mr Coates said to reduce the backlog last year, Chief Justice Alan Blow had provided extra sitting time in Burnie and on occasions a second criminal court in Launceston and a third in Hobart.

He said there was a "concentrated trial period in October/November" which had take much planning to organise.

"In addition to this, the Chief Justice suggested having further court time available for criminal matters," Mr Coates said.

"However, I informed him that unfortunately I did not have sufficient resources to meet such a request. This office does not have the capacity to continually service additional court sitting time whilst fulfilling its other functions."

Despite an increased work output, Mr Coates said the criminal backlog had increased from 443 in the previous year to 627.

He said there had been a "dramatic increase" in bail applications from 304 in 2016-17 to 414 in 2018-19.

Of the 414 bail applications only 130 were granted.

Mr Coates also expressed concern about delays causing "witness fatigue" with witnesses no longer wanting to give evidence.

"I have noted the discharge rate for sexual assault matters has increased significantly with the increase in the backlog," he said.