The lawsuit, brought by a Facebook users, accuses the firm of “intentionally and knowingly” transmitting personally identifiable information to third-party advertisers and internet marketing companies “without user consent and for a substantial profit”.

A Zynga spokesman said the complaint was “without merit” and that the company intends to defend itself “vigorously”.

The lawsuit makes reference to a Wall Street Journal investigation which named Zynga games among the Facebook apps found leaking user data to outside companies.

In the wake of the investigation Facebook acknowledged instances were user IDs (UIDs) had been disclosed, but in a blog post Facebook’s Mike Vernal said: “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.”

News of the Facebook app data leak followed revelations of similar issues with iPhone and Android applications.