"Technical staff is working to restore the security of the new bookings. No data has been stolen," D’Amato said in a statement.
The regional authorities are in constant contact with the office of the COVID-19 Emergency Commissioner in Italy, General Francesco Paolo Figliuolo, to ensure that vaccinated users receive their green passes as planned, the health commissioner added.
Starting from 6 August, Italians will be required to hold health passes to access indoor restaurants, long-distance trains and events such as festivals, concerts and sports tournaments.
Hackers attacked the website on Sunday night, demanding a ransom in Bitcoin, according to national media. As of Monday, the regional data centre is still down. An investigation into the incident is underway.