NEW YORK (CNN/Money) - Kohlberg Kravis Roberts & Co. is in advanced talks to buy a majority stake in the commercial mortgage business at General Motors' finance arm, GMAC, for at least $1 billion, according to a published report.

The New York Post reported Tuesday that as part of the negotiations, KKR is also expected to assist GMAC in refinancing some $3 billion to $4 billion.

GM (Research), the world's leading auto manufacturer, has been hit with losses at its core automotive operations but has been helped by strong results from GMAC. The commercial mortgage business is only a small part of GMAC's line of business, which also includes auto finance and home mortgages.

GM reached an agreement last year to sell the commercial mortgage unit to Deutsche Bank AG, the Post reported, but the sale fell through. GM is now under pressure to sell the unit in an attempt to shrink its $300 billion in debt and avoid the risk of a credit downgrade. Earlier this month, the company warned of an unexpected steep loss in the first quarter.

GM was not available for comment to the Post. Last week, a company spokeswoman confirmed to the Wall Street Journal that it is exploring a possible sale of the unit, but added that GM intends to keep a stake in the business even if it sells majority control.

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