Tasmanian Premier Peter Gutwein says the state will introduce the "toughest border measures in the country" to prevent the spread of coronavirus.

Key points: All "non-essential" travellers to Tasmania will need to self-isolate for 14 days

All "non-essential" travellers to Tasmania will need to self-isolate for 14 days The new measures will attract a penalty of up to $16,800 or six months in jail

The new measures will attract a penalty of up to $16,800 or six months in jail A state of emergency has been declared, giving power over to the Police Commissioner

From midnight on Friday, all "non-essential" travellers into the state will have to go into 14 days' quarantine, he said.

Mr Gutwein said "essential" travellers included people required to keep the state's health system and trade operational.

All others, including returning Tasmanians, will be required to go into quarantine.

Mr Gutwein said he "made no apologies" for the new restrictions, but reiterated that Tasmania's borders would not be closed to trade.

"We know that for some it will create disruption, but our aim is to ensure that we protect the health, wellbeing and safety of Tasmanians and we would ask people to work with us as we implement these measures and as they are managed over coming weeks," he said.

"I want to be clear to all Tasmanians, we are not going to shut the borders to those supplies that we need."

"Our ships will continue to run, the TT Line [the operator of the Spirit of Tasmania ferry between Melbourne and Devonport], will have, I expect, more opportunity to carry more freight into the state as a result of the fact that there will be, I expect, less people travelling."

All travellers arriving in Tasmania, including those returning home, will be asked to fill out a Tasmanian Arrivals Card, which will help the Government keep track of them.

The arrivals card was announced on Monday, and initially only applied to overseas visitors —159 have been filled out to date.

Mr Gutwein said the restriction may not automatically apply for people travelling for medical treatment and there would be "exemptions on compassionate grounds that would be dealt with on a case by case basis".

There had been calls from some in the community to shut Tasmania off from the mainland altogether, but legal experts warned that would be in conflict with Australia's constitution and could end in a High Court challenge.

Failure to self-quarantine could attract $16,800 fine

Mr Gutwein also said the new measures would carry penalties.

"I want to make it very clear that we expect people to abide by the law. There can be no excuse for not self-quarantining, for not abiding by the rules," he said.

"We will ensure that we monitor and keep in touch with people.

"Should somebody break the law, we will ensure that the full weight available to us under the laws, which would be up to a $16,800 fine or up to six months in prison, that those penalties are brought to bear."

State of emergency declared

Mr Gutwein said a state of emergency would be declared in Tasmania today.

He said that meant Police Commissioner Darren Hine would have the ability under the Emergency Management Act to take resources from other departments when and if he needed them.

Mr Gutwein said Tasmania's response to the pandemic had been "proportionate and scalable".

Tasmania has had 10 confirmed cases of COVID-19.

The most recent cases, confirmed on Wednesday, were a woman in her 40s who had recently travelled to the UK and two men in their 40s who had travelled together to several European countries.

Public health director Mark Veitch said all three had arrived in Tasmania before the Federal Government's mandatory 14-day self-isolation period for international travellers set in, but chose to remain in quarantine anyway.

"It was most helpful that these people returning from overseas were thoughtful enough that they could have coronavirus, and stayed at home," Dr Veitch said.

He said authorities were in the process of tracing passengers on the same flights as the three travellers who were seated near them.

On Wednesday, a number of large-scaled events were cancelled around the state, including the popular Salamanca Market, and Agfest, the state's largest agricultural expo.

'Dire situation' for state's tourism industry

Luke Martin, the head of Tasmania's tourism industry council, said the mandatory isolation period would drive some tourism businesses even closer to the wall, and urged owner-operators to get on the front foot.

"It's become a pretty day-by-day, dire situation for us," he told ABC Radio Hobart.

"We can't sugar coat this — this is a solvency question. The challenge is the uncertainty of how long this could go for."

He said businesses needed to take action quickly.

"Call your accountant, call your bank," he said.

"Essentially don't let the situation just become ongoing particularly for the owner operators and the small businesses that have tight margins and outgoings.

"Call the government hotline and make sure you're familiar with what assistance is available."

Mr Martin said hotel operators were now talking with the Government about how their empty rooms could be used.

"Some hotels will need to keep operating to provide self-isolation provisions," he said.

"That's been a lot of the conversation over the last couple of days. The Government released some advice yesterday to the sector on procedures they need to follow, so any businesses in that position need to follow that public advice."

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Flights already cut

Meanwhile, Qantas and Jetstar flights into Tasmania have been heavily cut.

The airline this morning announced it was standing down two thirds of its staff, and suspending all international flights until the end of May, as it deals with plummeting demand amid the coronavirus pandemic.

Qantas's Melbourne to Hobart flights have been cut from 26 per week to nine, while Sydney to Hobart flights have gone from 17 to seven.

Jetstar flights are also reduced, with Melbourne to Hobart down from 36 to 14, and Launceston to Melbourne from 26 to 14.

Jetstar Sydney to Hobart and Sydney to Launceston flights have also been significantly reduced.

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