SAN FRANCISCO -- Apple on Friday rid its App Store of some applications that it said could snoop on people's data and posed a security threat.

While Apple did not disclose which apps were pulled from its virtual shelves, the list was reported to include software capable of blocking ads from appearing inside other applications such as Facebook.

"We've removed a few apps from the App Store that install root certificates which enable the monitoring of customer network data that can in turn be used to compromise SSL/TLS security solutions," Apple said in an email response to an AFP inquiry.

"We are working closely with these developers to quickly get their apps back on the App Store, while ensuring customer privacy and security is not at risk."

The security concern centered on the ability of installed root certificates to route data in a way that allows for what is known in the hacker world as a "man-in-the-middle" attack.

Data from mobile devices, even if it is encrypted, could be sent through an intermediary computer server and inspected.

Ads are a source of revenue for many apps, including Apple News. The California-based technology giant shares in revenue generated in any applications on its mobile devices.

The newest software powering Apple mobile devices allows apps that block ads from pages while surfing the Internet using Safari web browser but does not extend that capability into applications people use.

While blocking ads promised to make surfing the Internet from iPhones or iPads faster and rein in telecom data use, it also sabotages what has long been the main way websites make money while providing free content or services.