Idle money in South Korea soared to a new all-time high, data showed Thursday, as investors continued to dither amid low interest rates and growing uncertainties ahead of a potential U.S. rate hike.

Short-term floating money reached a record 921.8 trillion won ($790.2 billion) as of end-September, up 21 percent from a year earlier, according to the data compiled by the Bank of Korea and the Korea Financial Investment Association.

Such money has been on the increase in recent years, rising 7 percent in 2013 and 11.5 percent last year.

Short-term floating funds refer to money moving in and out of investments in search of higher profits. They include cash, savings deposits with a maturity of less than six months, money market funds and repurchase agreement balances.

The surge is attributable to a fall in borrowing costs, which dragged down overall deposit rates at banks, prodding customers to search for high yield-generating investment tools.

The BOK cut the benchmark interest rate to a record low of 1.5 percent in June and has frozen the level till this month amid a looming U.S. rate hike and still weak local demand.

"Ample liquidity is out there, but low growth and uncertainties appear to have prevented investors from making longer-term investments," said Hyundai Research Institute researcher Kim Chun-koo.

Also responsible was the growing market uncertainties ahead of the looming Fed rate hike.

"The potential rate hike likely caused investors to take to the sidelines while opting for safer means of investment," said Byun Jun-ho, an analyst at Eugene Investment & Securities. (Yonhap)