The outbreak grew to 31 on Thursday after a high school student and man in his 40s tested positive.

Tasmanian Premier Peter Gutwein said border restrictions would remain in place for SA arrivals, but an update would be provided in coming days.

"As it stands, the medium-risk arrangements will remain in place," he said.

State Public Health Director Mark Veitch said it was important to take a cautious approach to avoid "flip flopping" on quarantine requirements.

Mr Gutwein confirmed a 'mercy flight' to repatriate Australians stranded overseas would touch down on the island state on December 6.

The charter plane from Delhi is part of Tasmania's pledge to host 450 returning international travellers across three flights.

They will be tested before leaving India and must have a negative test before being allowed out of two-weeks isolation in Hobart.

Mr Gutwein said police would manage and supervise hotel quarantine, and private security would only be used to monitor doors and exits.

Tasmania will also welcome 150 workers from Timor Leste in early December to help out with fruit picking.

They will be required to quarantine for a fortnight before beginning work.

Some 6000 Tasmanians have signed up for the summer work, about two times the usual figure.

Tasmania will drop border restrictions with Victoria on Friday for the first time in eight months, meaning it will be open to all states and territories bar SA.

Australian Associated Press