* Loss $767 mln vs loss $2.5 bln a year ago

* Mortgage division loses $747 mln (Adds CFO comments)

NEW YORK, Nov 4 (Reuters) - GMAC Financial Services, a lender that has received $12.5 billion in government bailouts, posted a third straight quarterly loss on Wednesday, hurt by red ink in its mortgage business.

The third-quarter net loss for Detroit-based GMAC was $767 million, compared with a loss of $2.5 billion a year earlier.

GMAC's auto finance unit had a profit of $395 million in the quarter, while its mortgage operations posted a loss of $747 million.

The lender has struggled as the deteriorating auto and housing markets have caused financing volume to decline and credit losses to increase. GMAC's owners include automaker General Motors [GM.UL] and the private equity firm Cerberus Capital Management LP [CBS.UL].

GMAC said that during the quarter some businesses -- including its U.S. consumer property and casualty insurance business and some financing business in Argentina, the UK and Italy -- were classified as discontinued operations.

Excluding those businesses, its loss from continuing operations was $671 million, it said.

"We continue to work through solutions for certain legacy assets, and that is still weighing on GMAC's financial performance," Chief Executive Alvaro de Molina said in a statement.