A chamber of commerce on Sydney's north shore has been forced to back down from comments demanding local businesses refuse entry to customers and staff who had not downloaded the COVIDSafe tracing app.

Ku-ring-gai Chamber of Commerce secretary Peter Vickers said he emailed between 1500 to 2000 businesses across its local government area on Monday directing them to ensure their customers had downloaded the app.

"It is very important that all businesses inform both their team members and customers that any visitors to businesses in Ku-ring-gai must be carrying a mobile phone with the Covidsafe app operating on it," Mr Vickers said in the email.

Under the rules governing the operation of the COVIDSafe app, it is illegal to coerce a person to download the app or refusing them service for failing to do so. Credit:Alex Ellinghausen

"Staff and customers should not be admitted to your premises unless they have the app operating."