American International Group (AIG) is looking to raise about $6 billion by selling part of its stake in Asia subsidiary AIA Group Ltd <1299.HK> in a long-awaited move to help the bailed-out U.S. insurer repay the federal government.

AIG is offering about 1.7 billion shares in a range of HK$27.15-27.50 per share - a discount of up to 7 percent to Friday's close of AIA's shares - according to a term sheet seen by Reuters. Earlier on Monday, trading in AIA shares was suspended.

In a statement on Monday, AIG announced the sale, via a placing with institutional investors, but did not specify the amount.

The U.S. insurer said it expects to use the net proceeds to reduce the balance due to the U.S. Treasury Department's preferred equity interest in a special-purpose vehicle in which AIG holds the AIA shares.

Goldman Sachs and Deutsche Bank are handling the share sale, according to two sources with direct knowledge of the process.

AIG is doing this sale at the right moment, said Kenneth Yue, a Hong Kong-based analyst at CCB International. If you look at the new business growth of AIA last year, it went up by 40 percent. I believe they've gone to the peak already - it would be very challenging for them to increase their new business value going forward by 40 percent every year.

While Yue believes AIG is getting a good price for its AIA stake, he said AIG's ownership will remain an overhang for AIA until the U.S. insurer sells out completely.

AIA, now Asia's third-largest insurer, was AIG's Asia arm until it was forced to spin it off following the U.S. government's rescue of AIG after the 2008 financial crisis.

AIA went public on the Hong Kong stock exchange in 2010, in a $20.5 billion IPO - still the third-largest public listing in Asia. The pricing of the AIA share placing by AIG will occur no later than Tuesday, the company said.

AIG shares are held inside a special-purpose vehicle, in which the U.S. Treasury has a preferred interest. At one time, AIG was expected to sell the AIA shares outright to pay off the Treasury, though in recent months the company has suggested it could keep some of the stake.

The Treasury Department still owns 77 percent of AIG, following the company's $182 billion bailout. At AIG's current stock price, the government is holding around a $4.7 billion loss on the stake, and CEO Robert Benmosche has said the Treasury was unlikely to sell until it could do so profitably.

AIG's total stake in AIA is worth $14.9 billion.

AIG can sell around $8 billion of its stake based on the terms of its ownership of AIA shares. The lock-up on the remainder of its stake expires late next month.

AIG is selling at an opportune time. AIA shares have risen 47 percent since early-October, and last week touched a 7-month high. The shares closed at HK$29.20 on Friday.

(Additional reporting by Fiona Lau and Ben Berkowitz; Written by Michael Flaherty; Editing by Ed Davies and Ian Geoghegan)