The world’s largest manufacturer of SIM cards was reportedly hacked by both U.S. and U.K. spy agencies, in what is another privacy scare for cellphone users.

A new report by The Intercept claims that the hacking of SIM cards enabled the agencies to spy on the activity of mobile phones worldwide, writes Alanna Petroff of CNN. Glenn Greenwald, the former Guardian journalist who worked in conjunction with Edward Snowden to bring the National Security Agency’s spying programs to light, is the co-founder of The Intercept.

U.S. And U.K. Spies Hacked SIM Cards

SIM card hack with global ramifications

The report draws on documents provided by Snowden, and claimed that the NSA and GCHQ hacked into SIM card manufacturer Gemalto in order to obtain the encryption keys, which allow access to SIM cards around the world.

Netherlands-based Gemalto is said to make around 2 billion SIM cards per year. Its customers include AT&T (T, Tech30), T-Mobile (TMUS), Verizon (VZ, Tech 30) and Sprint (S) as well as around 450 other global telecom firms, states the report. The manufacturer also makes chips for credit cards and has partnerships with more than 3,000 financial institutions.

Based in the Netherlands, Gemalto reportedly makes two billion SIM cards per year. Clients include AT&T (T, Tech30), T-Mobile (TMUS), Verizon (VZ, Tech30), Sprint (S) and about 450 other global telecom firms, according to the report. It also makes chips for credit cards and works with over 3,000 financial institutions.

Internal investigation ongoing

The hacking reportedly ran from 2010 to 2011. Gemalto takes great pride in its digital security record, and said it was not aware of the hacking operation.

“We cannot at this early stage verify the findings of the publication and had no prior knowledge that these agencies were conducting this operation,” the company said in a statement.

Gemalto is to carry out its own internal investigation into the matter. In morning trading in Europe the company’s share price dropped 7.5%.

The Snowden affair continues to have repercussions, and we can surely expect more revelations from The Intercept. The scope of surveillance by government agencies continues to amaze, and this SIM card hack could have affected billions of people.