WA Health has issued new advice for returned travellers from New South Wales after a Victorian man visited the state while unknowingly infected with COVID-19.

Anyone who has been to an exposure site is required to get tested and self-quarantine until receiving a negative test result.

The man was included in the six new cases announced in Victoria today.

Meanwhile, Melbourne will be in lockdown for at least the next week.

The Victorian government announced on Wednesday it would be extending the lockdown for another seven days until June 10.