NSW Premier Gladys Berejiklian has announced a slate of new restrictions for Greater Sydney as the COVID-19 outbreak grows.

30 new cases were recorded in the last 24 hours, with about 28,000 tests carried out.

28 of those have been linked directly to the Avalon cluster and the other two are residents of the northern beaches.

Residents in Greater Sydney will not be allowed more than 10 people in the home until midnight on Wednesday.

All indoor venues will now be subject to the one person per four sqm rule with a cap of 300 people.

No dancing will be allowed, apart from 20 people at a wedding, to prevent a spread of the virus.

Residents of the northern beaches are only allowed to leave their homes for essential reasons until midnight on Wednesday.

Health Minister Brad Hazzard is asking residents of Greater Sydney to wear masks.