bbcnews | The Dutch Sim card maker at the centre of NSA-GCHQ hacking claims has said it believes that the US and UK cyberspy agencies did indeed launch attacks on its computer systems.
However, Gemalto denied that billions of mobile device encryption keys could have been stolen as a result.
The Intercept alleged last week that spies had obtained the "potential to secretly monitor" voice and data transmissions after hacking the firm.
Gemalto operates in 85 countries.
Its clients include AT&T, T-Mobile, Verizon and Sprint among more than 400 wireless network providers across the world.
GCHQ and the NSA have not commented directly on the allegations.
Fake emails
In a statement, Gemalto said it had carried out a "thorough investigation" following the claims, which were based on documents leaked by whistleblower Edward Snowden.
"The investigation into the intrusion methods described in the document and the sophisticated attacks that Gemalto detected in 2010 and 2011 give us reasonable grounds to believe that an operation by NSA and GCHQ probably happened," the company said.
It highlighted two "particularly sophisticated intrusions" that it suggested the agencies were responsible for.
