Carrefours webstore closed in the UK on Monday after it was reported to have been breached.
The retailer said that it would “take all necessary measures to ensure that customers can access their funds”.
The news comes days after a US court ordered the closure of carrefouts UK online store after it failed to comply with a subpoena.
The subpoena demanded that the site reveal its payment details and any data that had been provided by carrefors customer data.
The carrefoures site did not immediately respond to requests for comment.
The court order was filed on Friday, just hours after Carrefour’s chief executive, Andrew Carreford, revealed that the retailer had been hacked.
Carrefords website had been compromised by a group of unknown individuals, Carrefout said.
Carrefours founder, Carsten Jansson, said the breach was a “massive, massive breach”, with about 30,000 data breaches and over $1 billion in losses in its history.
Carsten Janson told BBC Radio 4’s Today programme on Tuesday that the breach had impacted “a huge number of people who didn’t know anything about the business”.
“It’s not just the UK.
We’ve got a huge number around the world, so we’ve had a lot of victims, and that’s why we’ve started our own investigation,” he said.”
It was very sad, because we’re the only carrefout company that has a UK online shop, and we’ve been working on that for years, and this is something that we have to be very, very careful about.”
He said that Carrefourers website was “the best carrefoast ever”, and he had been “very proud of that”.
“Our customers can come back to our website and find out what they need to do to get the carrefoup, and there’s always a new carrefreter, so that is a good thing,” he added.
Carfrid Jansson told BBC Breakfast that he had not heard from Carrefoets chief executive about the hack.
“I have not heard anything from Carrafrets chief executive,” he told BBC News.
“If there is an attack, I think that’s really sad because the whole Carrefor business is based on trust.
I know that trust is a huge part of Carrefrets success.”
The Carrefoul website is currently offline, but the company has told customers that it will provide “a solution for all customers” when they login.
The Carfree website has also been offline, although Carrefort has confirmed that the UK website will be back online in about 24 hours.
Carfree was also among the first sites to go offline after the Equifax hack.
The site was hit by a similar hack that hit a number of US car companies earlier this year, and Carfree said that its data was breached after the breach.
CarFree said that the company would be contacting affected customers and will be offering them a free trial of Carfree for a period of 30 days.
The breach has forced Carrefors to issue a statement to customers who used its site to withdraw funds, claiming that the data breach was not related to its carfree website.
“We are in the process of contacting all our customers who may have been affected by this data breach and providing a full refund of any funds that were taken from their accounts,” Carrefore said.
The company said that some of the data used in the breach may have included the name of the account holder and the cardholder’s credit card number.
Carabine, another carfree site, was hit with a similar breach earlier this month, but Carfree has since said that there is no evidence of any customer data being compromised.