Federal prosecutors and New York's attorney general said Monday they had taken the unusual step of joining forces to probe the multitrillion-dollar credit-default swap market, an unregulated area of finance blamed for helping to fuel the credit crisis.

The offices of U.S. Attorney Michael Garcia and New York Attorney General Andrew Cuomo acknowledged the unique arrangement in separate statements.

"The attorney general believes that these unprecedented times call for unprecedented levels of effort and cooperation to ensure that our markets are stable, free of fraud and purged of corruption," Cuomo spokesman Alex Detrick said.

He said the joint probe was "aimed at restoring and promoting confidence and stability in the market" and avoiding multiple competing investigations.

Yusill Scribner, a Garcia spokeswoman, said prosecutors wanted to determine if federal laws were violated.