Finance company GMAC LLC will get emergency funding of up to $750 million from equity firm General Motors Corporation and Cerberus Capital Management LP.

This is part of a $3.5 billion financing package that will help GAMC's battered Residential Capital LLC mortgage unit avoid a cash shortfall.

The cost would be split between GM and the Cerberus affiliate Residential Funding Corporation according to their stakes, GMAC said in a filing with the Securities and Exchange Commission.

GM, the world's biggest automaker, and Cerberus, the New York-based private equity firm, may pay debt holders as much as $750 million if ResCap defaults, the Detroit-based auto and home lender said in the filing.

GM, which sold 51 per cent of GMAC to Cerberus-led investors in 2006, had earlier said it had no obligation to support ResCap after the GMAC unit was battered by subprime mortgage losses.

ResCap, ranked among the 10 biggest US mortgage lenders last year, may liquidate some assets, including mortgage securities, secured loans to raise an additional $600 million.

It may also arrange whole loan sales and could market businesses unrelated to mortgage finance, GMAC said in the filing.

GMAC said the mortgage unit posted about $5.3 billion in losses over the past six quarters.

Earlier this week, ResCap said it was in talks with GMAC for another $350 million of debt retirement and is using $150 million from a line of credit extended by the auto and home financier.

The company said it would need the funds by the end of June to avoid "negative liquidity," even with the $3.5 billion credit facility and a successful issue of $14 billion in bonds.

ResCap was one of the top 10 US residential lenders in 2007, and the largest independent mortgage lender behind Countrywide Financial Corp.