Victoria has closed its borders to NSW and the ACT, with the entire region becoming a "red zone".

Health authorities made the decision after NSW recorded 77 new COVID-19 cases yesterday.

When midnight struck travellers from NSW and the ACT were no longer permitted to travel to Victoria, with some exceptions.

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Victorian residents can obtain a red zone permit and return home but they will be required to immediately isolate, get tested, and quarantine for 14 days.

Exemptions are also available for essential workers, while border community residents can cross over in a limited capacity but must carry proof of address.

Anybody attempting to enter Victoria illegitimately will be fined up to $4957.

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Travellers from existing orange zones in NSW and the ACT were able to enter Victoria until 11.59pm yesterday tonight if eligible, including on flights.

But they must isolate on arrival, get tested within 72 hours, and stay isolated until they return a negative result.

Visit the Vic Health website for more information on the state's travel permit system.