LONDON — Gemalto, a French-Dutch digital security company, said on Friday that it was investigating a possible hacking by United States and British intelligence agencies that may have given them access to worldwide mobile phone communications.

The investigation follows news reports on Thursday that the National Security Agency in the United States and the Government Communications Headquarters in Britain had hacked Gemalto’s networks to steal SIM card encryption codes.

The claims — reported on a website called The Intercept — were based on documents from 2010 provided by Edward J. Snowden, the former N.S.A. contractor.

The American and British intelligence agencies are said to have stolen the encryption key codes to so-called smart chips manufactured by Gemalto, which are used in cellphones, passports and bank cards around the world.