The hacker group, known as Deus, claims to have broken into Voiceneter - a company that provides telephony services to Israeli companies. The attack began last Friday.

In the telegram channel they set up, they began leaking recorded conversations with customers, along with personal information, and offering the database - in a volume of 15 terabytes - for sale online.

Among other things, the company provides services to Israeli companies such as Partner, Gett, the cellular provider 018 and Mobilai.

"If it is this type of information and this amount, it is probably the biggest information leak that has been seen in Israel," says Ido Naor, CEO of the cyber company Security Joes.

Image: Reuters