On Thursday, the US subsidiary of Germany's Telekom announced that hackers had stolen the personal information of about 15 million people who had undergone credit checks through the Experian agency between September 2013 and September 2015 as a condition of signing up for wireless service.

Experian officials said they had immediately notified law enforcement authorities after discovering the hack and that "there is no evidence to-date that the data has been used inappropriately."

"I am incredibly angry about this data breach," T-Mobile US Inc. CEO John Legere said in a statement released late Thursday, "and we will institute a thorough review of our relationship with Experian." He said that the 15 million people hacked were not necessarily all T-Mobile customers - some had been turned down after Experian's credit check.

T-Mobile has called on affected customers to "remain vigilant" against identity theft and watch for phishing email scams that ask for sensitive information such as bank account and Social Security numbers. Customers can sign up for two free years of credit monitoring services through Experian should they wish.

US hacks

Hacks have recently hit several US businesses and organizations, affecting millions of people. Those who have found themselves embarrassed by data leaks include clients of the adultery website Ashley Madison, higher-ups at Sony Pictures, the insurer Anthem, retailers such as Home Depot and Target, the Web commerce site eBay, and even the federal Office of Personnel Management.

US organizations reported nearly 800 data breaches last year, according to the Identity Theft Resource Center.

In 2008, the German parent branch of Telekom found itself in hot water after it emerged that company security officials had endeavored to spy on workers and journalists to figure out who had leaked news to the press. That same year, the international cycling team sponsored by the company was reported to have engaged in widespread doping.

mkg/jm (Reuters, dpa, AP)