WASHINGTON BUREAU — American International Group Inc. (NYSE:AIG) has paid almost $4 billion back to the Federal Reserve Bank of New York.

AIG, New York, now owes $15 billion in principal and about $6 billion in interest and fees on a New York Fed revolving credit facility set up in March 2009, a company spokesman says.

AIG’s credit agreement calls for the New York Fed to lower the amount of credit available as AIG reduces the balance. The total amount of New York Fed credit available to AIG will drop to $30 billion, from $34 billion, according to a document AIG filed with the U.S. Securities and Exchange Commission.

In addition to backing the AIG credit facility, the New York Fed has provided help through two partnerships, Maiden Lane II L.L.C. and Maiden Lane III L.L.C. The partnerships invested in AIG residential mortgage-backed securities and asset-backed collateralized debt obligations at a time when credit markets were frozen.

AIG says it made the credit facility payments using cash generated by its International Lease Finance Corp. (ILFC) unit.

New York Fed officials declined to comment but seem to be pleased.

ILFC has regained access to private credit markets: It raised $4.4 billion this month by selling secured and unsecured notes to investors.

AIG will have to take a $650 million pretax accounting charge in connection with the re-payment, to reflect accelerated amortization of a prepaid commitment fee asset, but the payment will free about $10 billion in ILFC collateral that was pledged to the New York Fed, AIG says.

AIG President Robert Benmosche says in a statement that AIG is getting stronger every day.

Efforts to close on the sale of one Asian insurance business, American Life Insurance Company (ALICO), to MetLife Inc., New York (NYSE:MET), are on track, and AIG continues to work on holding an initial public offering for another AIG Asian insurance business, AIA Group Ltd., Benmosche says.

AIG’s insurance businesses are profitable, client retention rates have stabilized, and surrender rates have improved to normal levels, Benmosche says.

“We are starting to see light at the end of the tunnel,” Benmosche says. “We still have more work to do, but we will finish the job and make sure we repay the American taxpayer.”