We recently reported that Gemalto, the world's largest SIM card maker, may have been the target of a hacking operation by spy agencies. The result was that billions people's calls, texts and emails could have potentially been monitored.
Today, Gemalto has come out and said that a 'massive' intrusion did not take place, but that an operation of a smaller scale by NSA and GCHQ "probably happened".
According to Gemalto, this attempt to intercept only breached the office networks and "could not have resulted in a massive theft of SIM encryption keys".
The company added that intelligence services would only have been able to spy on 2G networks as "3G and 4G networks are not vulnerable to this type of attack."
In 2010 Gemalto noticed "suspicious activity" from a third party that was trying to spy on its office network, however the company says it took immediate action to counter this.
According to Gemalto, it had deployed a "secure transfer system" at that time which meant even spying on 2G networks would have been very difficult, and 3G and 4G networks impossible.
"Gemalto will continue to monitor its networks and improve its processes," the company added. "We do not plan to communicate further on this matter unless a significant development occurs."