A mass cancellation of credit cards has occurred in the wake of a security breach at Wesco service stations and convenience stores in Michigan, US.

Financial institutions such as Fifth Third Bancorp, Community Shores Bank Corp and Family Financial Credit Union have re-issued cards to their customers following evidence of fraudulent transactions occurring a Wesco stores. Wesco is a Muskegon-based gas station and convenience store chain with 51 locations across Michigan.

According to Computerworld, Wesco has confirmed that it is currently investigating the possibility of credit card fraud associated with card use at its facilities. It is believed that credit card transactions processed between July 25, 2006 and September 7, 2006 may have been compromised.

No explanation has yet been given as to how the security breach may have occurred.

Both MasterCard and Visa have also confirmed an investigation into fraud concerns in the Muskegon area, without disclosing the location of the retailer.