Maurice Hank Greenberg, the former American International Group Inc chief executive, said the judge overseeing a New York attorney general lawsuit against him should be removed from the case because he is biased.

In a court filing, Greenberg said that New York State Supreme Court Justice Charles Ramos made improper statements about the reinsurance transaction underlying the case, calling it a criminal enterprise, and relied on inadmissible evidence.

Ramos was not open to adjudicating this case on the face of the admissible record, lawyers for Greenberg and his codefendant, former AIG Chief Financial Officer Howard Smith, wrote in the Tuesday filing.

The court's statements and conduct here, considered in totality, give rise to an appearance of impropriety that requires this court to recuse itself, they added.

A spokesman for Attorney General Eric Schneiderman did not have an immediate comment on the filing.

Greenberg has since 2005 defended the lawsuit originally filed by Eliot Spitzer, then New York's attorney general, and later pursued by successors Andrew Cuomo and Schneiderman.

The case involves a transaction involving General Re Corp, a unit of Warren Buffett's Berkshire Hathaway Inc , that boosted AIG's loss reserves by $500 million without transferring risk.

Greenberg and Smith were accused of helping structure two transactions, including General Re, to hide losses. The transactions led AIG to restate its 2001 to 2004 financial statements.

A trial before Ramos is slated to begin on May 2.

In oral argument last April, Ramos told lawyers on both sides that the attorney general's office has put together a devastating case, a very strong case, and we both know it.

Greenberg left AIG in March 2005 after nearly four decades at the helm. AIG in 2006 paid $1.64 billion to settle federal and state probes into its business practices, and in July 2010 agreed to pay $725 million to settle a shareholder lawsuit accusing it of accounting fraud and stock price manipulation.

The General Re transaction resulted in five convictions and two guilty pleas of former AIG and General Re officials. Buffett was not accused of wrongdoing.

The case is New York v. Greenberg et al, New York State Supreme Court, New York County, No. 401720/2005.

(Reporting by Jonathan Stempel and Dena Aubin in New York; Editing by Phil Berlowitz)