Casual and mobile game developer Digital Chocolate is attempting to sue social gaming giant Zynga over its continued use of Mafia Wars, claiming that the trademark is wholly owned by Digital Chocolate in regard to a mobile game released in 2004, well before Zynga’s Mafia Wars was unleashed.

In the court documents, filed at Courthousenews.com, pertaining to the case, Digital Chocolate’s lawyers claim that the company repeatedly made Zynga aware of its claim to the trademark.

In May 2009, Digital Chocolate claims that it was assured in writing that Zynga did not intend to pursue the trademark, shortly afterwards, Zynga filed a patent application with the US patent office (USPTO).

Digital Chocolate has now asked the court to issue an injunction banning Zynga from using the name, and forcing it to spend more than the game’s original marketing budget in a campaign of ‘corrective advertising’. It is not known how Zynga is responding to the claim.

Nearly two million copies of Digital Chocolate’s Mafia Wars and its sequels have been downloaded worldwide, while four million people were said to be playing Zynga’s game daily, just one year after release.