Citigroup Incorporated has agreed to pay Enron creditors $1.66 billion to settle a lawsuit over its responsibility in the energy-trading company's downfall, a group representing creditors said Wednesday. The largest U.S. bank also is abandoning $4.25 billion of claims against Enron, while Enron is releasing all claims against Citigroup. The bank said in a statement that it denies wrongdoing, and agreed to the settlements only to avoid the expense and uncertainty of litigation. The $1.66 billion payout represents about 60 percent of the $2.8 billion Citigroup set aside for legal payouts in litigation reserves. Citigroup is the last of 11 banks to settle with Enron creditors, and its payment is by far the largest. Such litigation with banks is returning over $5 billion to Enron creditors, the creditors said in a statement.