Tasmania has closed its border to Perth and southeast Queensland in response to coronavirus community transmission on the mainland.
The island state declared the WA capital and neighbouring Peel region high risk from 10am on Tuesday.
Thirteen local government areas in Queensland, including Brisbane, Ipswich, Logan, the Gold Coast and Sunshine Coast, plus Townsville and Magnetic and Palm Islands in the north, are considered high risk from 6pm.
No one can enter Tasmania from high-risk areas unless they have special permission from the deputy state controller.
The Queensland high-risk declaration covers anyone who has been in those regions since June 19, while the WA ban is backdated to June 22.
"I would stress to Tasmanians, if you don't need to travel interstate, don't travel," Premier Peter Gutwein said.
"Right now we have a number of states scrambling to get on top of the Delta strain of the virus."
Perth and Peel were sent into a four-day lockdown on Monday night after a second local COVID-19 case was recorded, a man aged in his 30s who tested positive to the Delta variant.
The thirteen Queensland local government areas are entering a three-day lockdown from Tuesday evening due to virus transmission.
Tasmania had already banned travel from Greater Sydney, the Blue Mountains, Central Coast and Wollongong.
Travellers from Darwin and two other NT LGAs are also banned, while Tasmania considers a host of premises in Victoria and New Zealand high risk.
Mr Gutwein said three workers, who returned from the Northern Territory's Granites mine where a person tested positive last week, have returned negative results in their first round of testing.
Two are quarantining at home, the other is in hotel quarantine.
Mr Gutwein said the state government is considering making face masks mandatory at major events.
Under current rules, masks are only mandatory at Tasmania's airports and at the Spirit of Tasmania ferry terminal in Devonport.
Mr Gutwein said the state has adequate supplies of AstraZeneca vaccines for people under 40 after it was announced on Monday night that the demographic was now eligible to receive the jab.
Almost 37 per cent of Tasmania's eligible population have received their first COVID-19 vaccine and more than 11 per cent are fully vaccinated.
Mr Gutwein said the state government was "in discussions" with the AFL about the prospect of Tasmania hosting additional matches.
Australian Associated Press
Sign up for our newsletter to stay up to date.