CIT Group Inc reported a $1 billion loss in the fourth quarter on Tuesday, excluding one-time items and accounting adjustments, as the recently bankrupt commercial lender was hurt by high borrowing and credit costs.

The U.S. company said in a regulatory filing that it would not return to profitability in 2010 under regular accounting rules. But it added that new, post-bankruptcy accounting measures would bring it back into the black this year.

CIT, which named John Thain its new chief executive last month, reported net income of $3.2 billion in the fourth quarter under the post-bankruptcy accounting, known as Fresh Start Accounting, or FSA. Thain is a former CEO of Merrill Lynch & Co and NYSE Euronext .

CIT received $2.3 billion from the U.S. government's Troubled Asset Relief Program in December 2008. That obligation was wiped out when it filed for bankruptcy in November. It emerged from bankruptcy the following month.

The reorganization resulted in a $10.4 billion net reduction in debt and had a $10.3 billion pre-tax benefit to fourth quarter results, the company said.

The results were largely in line with an estimate CIT gave on March 1 in which it forecast a loss of about $900 million.

Separately, the company said in the filing that Snap-on Inc -- the tool manufacturer that ended its joint-venture with the lender last year -- filed a demand for arbitration alleging CIT underpaid it during the course of the venture, claiming some $115 million in damages.

CIT denied the allegations and itself alleges Snap-on wrongfully withheld payments to CIT, claiming more than $110 million in counter damages.

CIT shares rose 2.8 percent to $37.20 in after-market trading.

(Reporting by Jonathan Spicer; editing by Bernard Orr and Andre Grenon)