"Now that we have links to the New South Wales outbreaks in Victoria, we are having to respond really quickly to get on top of that."
Since 21 December, every Australian state and territory has had a travel ban on people from Sydney. However, the new Melbourne cases are believed to be linked to a woman who visited before the restrictions came in, Victorian officials said.
What's the latest in Sydney?
Australia has 163 active local infections, with almost all of them tied to the outbreak in Sydney, which has worsened in recent days.
The re-emergence of the virus there in mid-December prompted the New South Wales (NSW) state government to impose swift restrictions on its capital, including limiting gatherings and locking down a section of the city.
These measures had appeared to be working, with the city reporting only single-digit daily case increases amid intense contact tracing efforts.
