The U.S. government's $2.65 billion operating loan program to help farmers keep their businesses going has already run out of cash, as requests for federal financial assistance grow amid the worst agricultural downturn in more than a decade, U.S. officials told Reuters on Monday. As a result, the U.S. Department of Agriculture is looking for other money sources "to help bridge the gap in farm operating loans as much as possible until additional funds are made available, either this year or in the next fiscal year," the agency said.

The agency declined to say what other funding it was hoping to leverage for assistance.

Such FSA loan guarantees and direct loans are often considered to be loans of last resort, say banking experts. Without the financial support, some farmers may struggle to survive until the next cash injection in the fall, say rural economy experts.

Last month, the USDA's Farm Service Agency told Reuters it had expected funding for these loans or guarantees to be depleted before the program restarts Oct. 1.

As the rural sector struggles with low commodity prices and mounting trade competition, U.S. grain farmers are increasingly relying on the FSA for loan assistance. Agricultural lenders, too, are turning to the agency to help guarantee the loans they are issuing to farmers - whether for operational or real estate needs.