T-Mobile US Inc said on Friday an ongoing investigation into a data breach revealed that hackers accessed personal information of an additional 5.3 million customers, bringing the total number of people affected to more than 53 million. The third largest U.S. wireless carrier had earlier this week said that personal data of more than 40 million former and prospective customers was stolen along with data from 7.8 million existing T-Mobile wireless customers. In its latest update, which comes days after the U.S. Federal Communications Commission (FCC) opened an investigation into the breach, T-Mobile revealed it had identified 5.3 million additional wireless subscribers who were impacted by the breach as well as 667,000 more accounts of former customers. The data includes addresses, dates of birth and phone numbers of customers, the company said, adding that it had no indication that the accessed data contained financial information such as credit card or …