US-based restaurant company Jason’s Deli has warned its customers of potential credit card data breach at different locations of its 266 franchise chain across 28 states.

The firm was notified by payment processors on 22 December 2017 that MasterCard security personnel found the appearance of a large quantity of payment card details for sale on the ‘dark web’.

An analysis showed that certain portion of the data might have come from Jason’s Deli. While further details of the breach have not been disclosed, the firm has reported initiation of a response plan.

The firm’s threat response team is working with forensic experts to establish if a breach has taken place and if so, its scope, technique and any remnant threat or vulnerability.

The firm has recommended its customers to monitor their payment card accounts and report any suspicious activity to card issuers.