Company has reassured investors after huge hacking was reported last week

Sim cards made by Gemalto are “secure” despite reports that GCHQ and NSA hacked the company’s databases, it said today.

Last week, reports said that the British and American intelligence agencies hacked into the company to find the Sim card encryption keys, allowing them to access the communications of anybody using the company’s products. Gemalto Sim cards are used by a huge proportion of the world’s mobile networks.

The company said in a statement: “Initial conclusions already indicate that Gemalto SIM products (as well as banking cards, passports and other products and platforms) are secure and the company doesn't expect to endure a significant financial prejudice.”

It will provide a full update on its investigations on Wednesday, it said. The company will hold a press conference in Paris that morning.

It was reported that last week that GCHQ and the NSA had hacked the database of encryption keys. The information found through the hack was likened to acquiring the master key for an apartment building – allowing whoever has it to bypass the locks that are supposed to stop people from listening in on or calls or other communications made with the Sim.

The hack was first reported by the Intercept last week and based on documents leaked by Edward Snowden.