Jan 24 (Reuters) - U.S. companies borrowed 9% more in December to finance equipment investments compared with a year earlier, industry body Equipment Leasing and Finance Association (ELFA) said on Tuesday.

The companies signed up for $12.9 billion in new loans, leases and lines of credit last month, compared with $11.8 billion a year earlier, according to ELFA. Cumulative borrowings were up 6% from January 2022.

ELFA, which reports economic activity for the $1 trillion equipment finance sector, said credit approvals totaled 76.6% in December, down from 77.7% in November.

"Not knowing yet the full impact of the Fed's series of rapid rate increases on the economy, I believe many companies will start the year with more focus on credit quality and spreads versus origination volume," said AP Equipment Financing's president, Chris Lerma.

Washington-based ELFA's leasing and finance index measures the volume of commercial equipment financed in the United States.

The index is based on a survey of 25 members, including Bank of America Corp, and financing affiliates or units of Caterpillar Inc, Dell Technologies Inc, Siemens AG, Canon Inc and Volvo AB.

The Equipment Leasing & Finance Foundation, ELFA's non-profit affiliate, said its confidence index in January stood at 48.5, an increase from 45.9 in December. A reading above 50 indicates a positive business outlook. (Reporting by Priyamvada C in Bengaluru; Editing by Shilpi Majumdar)