In violation of the social-networking giant’s own rules, many of Facebook’s most popular apps are sharing personally identifiable information of their users with dozens of advertising and Internet-tracking companies.

The company admitted on Monday that a number of major apps, including FarmVille, had been transmitting user IDs to advertising networks, which were in turn able to add the data to their own data piles and sell fleshed-out profiles of you, the consumer.

Data-gathering firm Rapleaf was able to link information gathered from those apps to its own database of Internet users, the report found. The San Francisco-based start-up provides a people search engine that lets you retrieve the name, age, and social-network affiliations of anyone, as long as you have his or her e-mail address.

“When we discovered that Facebook IDs were being passed to ad networks by applications that we work with, we immediately researched the cause and implemented a solution to cease the transmissions,” Rapleaf said in a statement. “As of last week, no Facebook IDs are being transmitted to ad networks in conjunction with the use of any Rapleaf service.”

Facebook stressed that the passing on of UIDs by developers to third-party organizations was “inadvertent”, and accused the press of exaggerating the scale and significance of the incident.

“Press reports have exaggerated the implications of sharing a UID. Knowledge of a UID does not enable anyone to access private user information without explicit user consent. Nevertheless, we are committed to ensuring that even the inadvertent passing of UIDs is prevented and all applications are in compliance with our policy,” wrote Mike Vernal, a Facebook engineer, on the company blog.

Some of the apps at the centre of the controversy were offline over the weekend, as developers sought to resolve the issue.