The hedge fund that successfully fought for more than a decade against Argentina has a new target: Mossack Fonseca.

In a grudge match playing out in federal court in Nevada, NML Capital Ltd., a unit of hedge-fund giant Elliott Management Corp. managed by New York billionaire Paul Singer, is suing the Panamanian law firm for obstruction of justice.

Mr. Singer zeroed in on Mossack Fonseca in 2013, as he searched the globe for Argentine assets his fund could seize as compensation for bonds on which Argentina had defaulted. Mr. Singer’s NML alleged the law firm set up shell companies in Nevada that were used to siphon stolen money from Argentina and then obstructed its efforts to uncover those links.

Earlier this year, NML reached a settlement with Argentina that would pay the fund $2.4 billion, but that doesn’t mean it is giving up on the Panamanian firm.

“Mossack Fonseca actively engaged in the concealment and destruction of evidence,” NML wrote in a filing with the U.S. District Court in Nevada in late May. “They should be held accountable for their conduct.”