U.S. dollar-denominated deposits at South Korea's five mainstream banks surged nearly 25 percent last year as investors flocked to safer assets amid lingering market uncertainties and ahead of a U.S. rate hike, analysts said Wednesday.

Local residents' U.S. dollar deposits at KB Kookmin, Shinhan, Woori, KEB Hana and NH Nonghyup Banks came to a combined $31.02 billion as of the end of last year, a 24.3 percent spike from 24.96 billion won logged at the end of January 2015, according to the banks' data. 

In November alone, $657 million flowed into the banks, as people apparently expect the greenback to strengthen following the widely expected U.S. rate hike, according to bank officials.  

Last month, the U.S. Federal Reserve ended the near-zero rate that had lasted nearly the past decade and raised it by a quarter point to 0.25-0.50 percent, while hinting at further belt-tightening in 2016.

The surge is attributable to the Korean won's steady decline against the dollar this year due mainly to the stock market rout in China.

On Tuesday, the local currency was trading at 1,210.3 won against the greenback, after briefly dipping to below 1,210 won for the first time since July 22, 2010.

"The deposits in the U.S. dollar are forecast to continue to rise at least in the first half of this year given wobbly global circumstances, including the economic slowdown in China and the subsequent appreciation of the dollar," said Chung Hee-soo, a researcher at Hana Institute of Finance. (Yonhap)