Tasmania will move to tougher COVID-19 restrictions, as authorities reveal two virus-infected travellers visited a string of popular tourist attractions last month.

Premier Peter Gutwein said an announcement would be made on Thursday afternoon.

“I’ve been taking further advice from the Director of Public Health and the state emergency controller over recent days,” he said.

“We need to do more to flatten the curve and we will have more to say on this matter.”

Mr Gutwein said the island state would keep its borders closed “for as long as we need to”.

• More information: Official Tasmanian coronavirus site

Tasmania’s virus tally rose overnight by one to 72.

It has also been revealed two interstate travellers had the virus while on an organised tour of the state from March 12-23.

They visited several tourist attractions, including MONA, Port Arthur, Cradle Mountain Visitor Centre, plus several farms, hotels and restaurants.

Tweet from @MonteBovill

They were unaware they had the virus until testing positive after returning to their home state, which has not been named.

Tasmanian Public Health Director Mark Veitch has urged anyone who develops virus symptoms after being at those locations to visit their GP or contact the public health hotline.

It is likely one of the pair was infected for the majority of the trip and the other from March 19.

Dr Veitch said he was confident one of the two caught the virus from outside Tasmania. He was unsure about the second person.

An investigation has been unable to find the source of two separate cases at Devonport, in the north-west, but Dr Veitch said community transmission could not be substantiated.

The state is yet to have a recorded case of community transmission.

Two people, a woman and man in their 80s, died from the virus in Tasmania earlier this week.

-AAP