The breach would give the agencies the potential to secretly monitor a large portion of the world"s cellular communications, including voice and text data.
"We are opposed to any country attempting to conduct intelligence gathering in cyberspace using its information technology superiority or IT products vulnerabilities," Hong Lei said at a press briefing.
Gemalto produces about 2 billion SIM cards per year. As of 2010, Chinese customers accounted for 45 percent of the chipmaker's SIM card sales, according to a ResearchInChina study.
Former NSA contractor Edward Snowden exposed the NSA practice of degrading private technology and communications companies' hardware to gain access to private data in a series of high-profile leaks beginning in 2013.
