A coroner's investigation into the death of a baby whose care was previously brought to the attention of authorities is clear proof Tasmania's child protection system is under-resourced, a union says.
The seven-month-old is believed to have drowned in a bathtub at a home in Launceston on September 19.
The baby was the subject of two child protection notifications in the fortnight prior.
Tom Lynch, secretary of Community and Public Sector Union which represents child protection workers, has described the death as an avoidable tragedy.
"Clearly it's a fault of the system and evidence there were insufficient resources to respond to the notifications," he said on Wednesday.
At a union rally this month, child protection workers said staff shortages had created a crisis in the sector.
Tasmanian Greens leader Cassy O'Connor and Labor opposition MP Josh Willie have also questioned the adequacy of child safety resources.
"I'm hearing stories about child protection workers who are extremely stressed," Mr Willie said.
A health nurse visited the baby and the parent eight days before the death, police say.
A coronial investigation has been launched and records from "a number of agencies" are being examined.
Premier Will Hodgman told reporters he was unable to comment as the matter was before the police.
"This matter will be subject to police investigation, no charges have been laid to this point," he said.
Human Services Minister Jacquie Petrusma has said the facts of the case were still unclear.
It comes three months after an inquest into the death of six-week-old baby Bjay Johnstone in 2012 found there had been "comprehensive failure" of child protection services, Tasmania Police and family members.
Bjay suffered a fractured skull, broken pelvis, broken ribs and legs and severe brain and eye damage at the hands of his violent father.
