Hackers claiming to be behind the theft of information about millions of current and former clients of telecoms company Odido are threatening to publish the data on the dark web unless the company pays them at least €1 million, broadcaster RTL said on Tuesday.

RTL said the hackers, which it named as the “Shinyhunters” group, have said they want a “low seven-figure sum” in cash.

The broadcaster published a screenshot of the demand, in English, which states: “this is the final warning to come back to our chat and finish what we set out to do before we leak”.

“You know where to find us,” the message said.

Shinyhunters, previously connected to hacks at Microsoft, Ticketmaster, Jaguar and Louis Vuitton, has provided evidence that they are indeed behind the theft, RTL said.

The cyber criminals also claim that the details of eight million Odido and Ben clients have been stolen, far more than the telecoms firm itself suggested. The stolen information includes names, addresses, phone numbers, bank account details and passport numbers.

The hack occurred via customer service workers’ accounts after the hackers were able to obtain passwords using phishing techniques, sources told broadcaster NOS earlier.

The hackers have given Thursday as the deadline for their demand to be met.