UPDATE 1-GMAC forgives some of ResCap's debt

(Adds background to ResCap, details on debt forgiveness)

NEW YORK, Dec 2 (Reuters) - Residential Capital LLC, the mortgage-lending arm of finance company GMAC, said its parent company is forgiving up to $683 million of its debt, to allow it to avoid defaulting on credit facilities.

ResCap must maintain a tangible net worth of at least $250 million to meet the terms of some of its credit facilities. The company's net worth shrank in November in part because it set aside more money for losses, and ResCap said its net worth could shrink more.

By forgiving loans that GMAC made to ResCap, the mortgage lending unit will maintain a tangible net worth of $300 million, ResCap said in the filing.

ResCap said GMAC has informed the company it may forgive additional loans or provide other support but it does not currently intend to take further action if GMAC's debt exchanges are not completed.

ResCap, based in Minneapolis, has had to cut costs and reduce lending risk as lower housing prices in many U.S. and international markets have led to higher delinquencies and defaults on loans it owns and services.

General Motors Corp (GM.N) owns 49 percent of GMAC and private equity firm Cerberus Capital Management LP [CBS.UL] owns the rest.

(Reporting by Elinor Comlay; editing by Gunna Dickson)