Dutch SIM card maker Gemalto investigating reported U.K.-U.S. hack

Exterior view of the building housing the head office of Gemalto, which produces "subscriber identity modules", or SIM cards, in Amsterdam, Netherlands, Friday, Feb. 20, 2015. Britain's electronic spying agency, in cooperation with the U.S. National Security Agency, hacked into the networks of Dutch company Gemalto to steal codes that allow both governments to seamlessly eavesdrop on mobile phones worldwide, according to the documents given to journalists by Edward Snowden. (AP Photo/Peter Dejong)

Gemalto said on Friday it was investigating a report U.S. and British spies had hacked its systems to steal the privacy-protecting encryption keys in the chips it makes for mobile phones.

Citing documents provided by whistleblower Edward Snowden, the report said the hack allowed the agencies to monitor a large portion of voice and data mobile communications around the world without permission from governments and telecom companies.

Gemalto's shares sank as much as 10 per cent in early trading after Intercept reported the hack by the U.S. National Security Agency (NSA) and Britain's Government Communications Headquarters (GCHQ).

"We take this publication very seriously and will devote all resources necessary to fully investigate and understand the scope of such sophisticated techniques," the company said in a statement.

The breach was detailed in a secret 2010 GCHQ document, Intercept said.

A spokesperson for GCHQ said the agency did not comment on intelligence matters. NSA could not be immediately reached for comment.