The incident, which Labor's Shane Broad suggested was potentially responsible for the outbreak of coronavirus on the North-West Coast, was revealed during the Primary Industries budget estimates on Thursday.

Primary Industries and Biosecurity Minister Guy Barnett along with DPIPWE Secretary Tim Baker and Biosecurity Tasmania acting chairwoman Rae Burrows were grilled by Dr Broad on the incident.

Dr Broad said he had been made aware of an incident at the Launceston Airport, where passengers from the Ruby Princess had been identified by Biosecurity Tasmania as high-risk based on their travel on the cruise ship.

The staff then relocated those passengers in an air-lock at the airport while they sought advice from the State Controller and from Public Health on whether the passengers were required to go into quarantine.

"There were flights with passengers returning from the Ruby Princess into Launceston; they were identified by Bioscecurity Tasmania as being internationals, they were kept in the airlock and then superior staff made the judgement to let them in, is that accurate," Dr Broad said.

Ms Burrows, who answered on behalf of the state government, said Biosecurity Tasmania staff acted carefully with regard to the Ruby Princess situation, but at it was something that happened at the beginning of the pandemic there were no strict protocols in place.

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"We were extremely conservative. At the time of the Ruby Princess we weren't aware of the full ramifications of what had happened," Ms Burrows said.

"They did what they were supposed to do, which was to keep high risk passengers away from anyone. We didn't have any protocol for the Ruby Princess because we weren't aware. The decisions were made with the best info we had at the time and with the safety of staff in mind."

Dr Broad and Greens Leader Cassy O'Connor pressed Mr Barnett on the chain of command that allowed those passengers to enter the state.

They also accused DPIPWE Secretary Tim Baker of holding the role of the State Controller at the time, which he categorically refused.

"At no time was I the State Controller; there was a time, for about two weeks I think where I was involved in approving essential workers, but at no time was I involved in border decisions," Mr Baker said.

Mr Barnett said at the end of the day, the decision was made by the State Controller, and he questioned the relevance of the questions from the committee.

However, Dr Broad accused Mr Barnett of "passing the buck" and throwing the State Controller under the bus on the decision, which resulted in Tasmanian deaths.

"No one is taking responsibility for the decision. In Budget Estimates this morning the minister responsible for Biosecurity Tasmania, Guy Barnett, attempted to wash his hands of the issue," Dr Broad said.

"This is a monumental stuff up and Tasmanians deserve to know how the decision was made and who made the final call."

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The incident occurred after Tasmania had banned all cruise ships from entering Tasmania and it occurred after the declaration of a Public Health Emergency.

The Ruby Princess was identified as the likely source of an outbreak that resulted in the lockdown of the North-West Coast and the shut down of the North West Regional Hospital according to an interim report from an inquiry into the matter.

Mr Barnett said the inquiry, which is underway, is expected to provide its final report to the state government at the end of the month, after a short delay.

The report was due to be finalised at the end of October.