A federal claims court judge ruled on Monday that Federal Reserve Chairman Ben Bernanke should testify in the former American International Group Inc. (NYSE:AIG) chief's case against the United States over the insurer's 2008 bailout.

The U.S. Court of Federal Claims judge Thomas Wheeler rejected the government's effort to keep the Fed chairman from being deposed, saying Bernanke was a "central figure" in the decision to bail out AIG.

"The court cannot fathom having to decide this multibillion-dollar claim without the testimony of such a key government decision maker," Wheeler wrote. "These facts constitute 'extraordinary circumstances' for the taking of Mr. Bernanke's deposition."

Maurice "Hank" Greenberg's Starr International Co. once had a 12 percent stake in AIG and is suing over the government's taking of a 79.9 percent stake in September 2008, plus a separate 1-for-20 reverse stock split in June 2009.