(Adds background about the cyber incident at HWL Ebsworth in...

(Adds background about the cyber incident at HWL Ebsworth in paragraph 2 and banks' response in paragraph 3)

June 20 (Reuters) - The big "four" banks in Australia said on Tuesday that their systems were not impacted by the cyber incident at law firm HWL Ebsworth.

In April, the commercial law firm fell victim to a ransomware attack from the hacking group ALPH/BlackCat that claimed to have client and employee data.

The top banks said their systems remain secure and that they are working with HWL Ebsworth to understand the potential exposure. The banks will also be contacting the employees and customers who may have been affected by the incident, they said.