--AIG sends $2.15 billion to U.S. Treasury to pay down bailout.

--Funds come from just-completed sale of Taiwan life-insurance unit.

--Treasury calls payment an "important milestone."

(Adds comment from Treasury in the fifth paragraph, details on TARP repayment in the ninth.)

NEW YORK (MarketWatch) -- American International Group Inc. AIG, +0.87% paid $2.15 billion it got from selling a Taiwan life insurance unit to the U.S. Treasury as part of its effort to repay its bailout, Treasury said Thursday.

The proceeds come from the sale of Nan Shan Life Insurance Co., a unit AIG had struggled to sell for months. AIG said in a statement Thursday it had closed the sale of the unit to a previously disclosed buyer, Ruen Chen.

Regulators in Taiwan had blocked a prior deal when they ruled an earlier buyer lacked financial strength and commitment to Nan Shan. But the regulator last month signed off on Ruen Chen, a cement-to-footwear consortium that AIG had picked when the first buyer was rejected.

The funds repaid another chunk of the AIG bailout, reducing the amount Treasury is trying to recoup from AIG asset sales to roughly $9.3 billion. AIG has earmarked other assets that can be sold partially or completely to pay down that remaining amount, including its stakes in pan-Asian life insurer AIA Group Ltd. and aircraft leasing firm International Lease Finance Corp.

"This is another important milestone in AIG's remarkable turnaround," said Tim Massad, Treasury's assistant secretary for financial stability, in a statement. "We continue to make progress in recovering the taxpayers' investments in AIG."

Treasury also holds 77% of AIG's common stock and is separately seeking to recover $41.7 billion from selling its majority stake in the company over time.

Overall, Treasury said it's received $313 billion in repayments and other income from its TARP investments. That's about 76% of the $412 billion disbursed under the program to date.

--Serena Ng contributed to this article.