Australia's Chief Medical Officer has walked back an earlier claim that staff from a Tasmanian hospital at the centre of a coronavirus outbreak attended an "illegal dinner party" together.

Key points: Brendan Murphy made his comments to a NZ parliamentary committee

Brendan Murphy made his comments to a NZ parliamentary committee Tasmania's Premier Peter Gutwein hit back, saying he didn't want health workers "maligned"

Tasmania's Premier Peter Gutwein hit back, saying he didn't want health workers "maligned" Mr Gutwein ordered police to investigate the allegations

On Tuesday morning Brendan Murphy told a New Zealand parliamentary committee that most of the people involved in a cluster of cases around the town of Burnie, including in the North West Regional Hospital in the state's north-west, went to the dinner party.

Tasmania COVID-19 snapshot Confirmed cases: 226

Confirmed cases: 226 Deaths: 13, 12 in north-west What do I do if I think I have coronavirus? If you think you might have COVID-19 phone your GP or the Tasmanian Public Health Hotline on 1800 671 738. Need an interpreter? Phone the Translating and Interpreting Service on 131 450 and tell them your language. For more information and factsheets: Visit the Tasmanian Government's coronavirus page here.

That drew a rebuke from Tasmania's Premier Peter Gutwein, who said Professor Murphy was commenting on a "rumour".

Professor Murphy later released a statement saying contact tracing had not confirmed such a dinner party took place.

"This morning … I referred to suggestion that a dinner party may have been the source of some of the transmission in the north-west Tasmania cluster of cases," he said.

"Whilst this possibility had previously been mentioned to me following initial investigations, I am now informed that the contact tracing has not confirmed that such a dinner party occurred."

Up to 5,000 people are now in quarantine after authorities ordered Burnie's North West Regional Hospital, and the North West Private Hospital, to close their doors. Sixty-six of Tasmania's 150 confirmed COVID-19 cases are linked to the outbreak.

Earlier, Mr Gutwein said police were investigating claims that staff had attended a party in contravention of social-distancing rules.

"To be frank, Brendan was commenting on a rumour," he said.

"At this stage, contact tracing has not identified a dinner party of health workers.

"However, I accept that this is a serious allegation and it's something that needs to be followed up.

"We will retrace our steps, but importantly I have asked that Tasmania Police investigate this matter and that will be started today."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 47 seconds 47 s Peter Gutwein says claims a coronavirus outbreak started after a dinner party are a rumour ( gutwein, tasmania, dinner party, brendan murphy, p )

Mr Gutwein said he wanted to get to the bottom of the rumour as soon as possible.

"We need to understand whether or not there is any strength to the rumour. At the end of the day, I'm certain that there are many hardworking health professionals on the north-west coast that feel that their reputations are being maligned," he said.

"Regardless of whether or not that party took place, it does not change the fact that we need to get on top of this outbreak.

"It does not change the fact that we need to all work together on the north-west coast and across the state to ensure that we follow the rules."

Speculation 'very distressing' for medical staff, union says

Emily Shepherd from the Australian Nursing and Midwifery Federation described the rumours as "baseless" and hurtful to staff who she said had been on the "frontline in the fight against COVID-19".

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"They're baseless, there's no evidence to support them and they'd sooner see the rumours shut down and the focus shifted to the public health inquiry and looking at what we can learn from the experience and ensure it doesn't happen in any other areas of the state."

"[Staff have] been on the frontline in the fight against COVID-19 trying to protect their community and to have this rumour circulating as they venture into 14 days isolation is very distressing," Ms Shepherd said.

"It's unacceptable and we would sooner see these rumours shut down."

Possible link to Ruby Princess being investigated

Tasmania's Director of Public Health Mark Veitch said he had "heard of some Facebook chatter".

"Our contact traces have not identified a medical meeting or a medical dinner party as one of the sources,' he said.

"But we need to go back, see whether there's any truth to it, see if it has any linkage at all to that occurrence."

Dr Veitch also said authorities were "exploring" the Ruby Princess cruise ship as "a source of the origin of the outbreak".

"But we are keeping our mind open. We will try and join the dots between the cases who were Ruby Princess cases and staff who became unwell, and that process is ongoing.

However, he said the information could be some weeks away.

The number of cases in the state increased by almost 50 per cent over the Easter period, with all 47 new cases linked to the north-west outbreak.

No new cases were identified in the past 12 hours and the state's total cases stand at 150, with 57 people now recovered, 88 active cases, and five deaths.