NSW Health is closely monitoring the situation in Victoria as local health authorities investigate four COVID-19 cases detected in Melbourne's northern suburbs.

The new cases visited a number of venues while infectious.

People arriving in Sydney from the Greater Melbourne area are reminded that they must complete a declaration which confirms they have not attended one of these venues of concern.

The declaration form is available on the Service NSW website, and can be completed in the 24-hour period before entering NSW or on arrival.

NSW Health will be contacting people who have completed declarations to ask them to check the Victoria Department of Health and Human Services website and immediately follow the outlined public health advice. Venues may be updated, so it is important to check this page regularly.

If you have been in Victoria since 10 May and attended any of the venues identified at the times listed, please contact NSW Health immediately on 1800 943 553.

The travel declaration provides critical information to enable NSW Health to contact travellers if required, and is for all travellers who intend to enter NSW by air, road and rail having been in Greater Melbourne in the previous 14 days.

This form includes contact details and confirmation of whether people have been to any venues of concern. Declaration forms can be completed within the 24-hour period prior to entering NSW, or on entry to NSW.

People who have been in the Whittlesea Local Government Area should not visit residential aged care facilities, or hospitals unless seeking medical attention.

The Whittlesea LGA includes the suburbs and rural localities of Beveridge, Donnybrook, Doreen, Eden Park, Epping, Humevale, Kinglake West, Lalor, Mernda, Mill Park, South Morang, Thomastown, Whittlesea, Wollert, Woodstock and Yan Yean.

There are more than 300 COVID-19 testing locations across NSW, many of which are open seven days a week.

To find your nearest clinic, visit: COVID-19 clinics or contact your GP.