Continuing their legal crusade against Facebook founder & CEO Mark Zuckerberg, Cameron and Tyler Winklevoss have filed a new lawsuit against the world’s most popular social network.

The Winklevoss twins filed a motion in Massachusetts, asking the court to determine whether Facebook’s counsel hid evidence in the form of instant messages that might have helped their case.

The motion claims that Facebook’s counsel knowingly hid online instant messages from earlier proceedings, and that said those instant messages would have proved their accusations against Zuckerberg.

The new motion was filed just a day after the twins said they would not go to the US Supreme Court to get a 2008 settlement with Zuckerberg undone.

It was in 2004 when Tyler and Cameron Winklevoss had dragged Facebook founder to the court, claiming that their Harvard classmate Zuckerberg had stolen their idea for the social network to found Facebook.

The two sides hit a $65 million settlement in 2008, but later Winklevoss twins rejected the settlement, saying Zuckerberg concealed the actual value of the company at the time of settlement.

Facebook is currently the world’s most popular social-networking site, with more than half a billion users around the globe.