South Korean banks' loan delinquency ratio jumped to a 15-month high in November due to surging sour loans in shipbuilding and real estate sectors, the country's financial watchdog said Wednesday.

The rate of bad loans overdue for more than one day reached 1. 43 percent of the total bank loans to companies and households as of the end of November, up 0.15 percentage points from a month earlier, according to the Financial Supervisory Service (FSS). The reading was the highest since 1.5 percent tallied in August 2010.

The November jump came after fresh delinquent loans to the shipbuilding and real estate sectors grew sharply, according to the FSS. The delinquency ratio for loans to shipbuilders climbed to 17.87 percent as of the end of November, up 7.07 percentage points from the previous month, with the rate for project- financing real estate loans gaining 0.77 percentage points to 9.61 percent over the cited period.

Seasonal factors also contributed to the growth as domestic banks were reluctant to resolve overdue loans after the quarter- end book closing, the FSS said.

Meanwhile, new delinquent loans amounted to 3.4 trillion won (2. 97 billion U.S. dollars) as of the end of November, down 0.5 trillion won from a month before, but overdue loans resolved grew 0.4 trillion to 1.6 trillion won over the same period.

The delinquency ratio of banks' corporate lending came in at 1. 99 percent in November, up 0.26 percentage points from the previous month. The default rate for large corporations climbed 0. 57 percentage points on-month to reach 1.93 percent as of end- November, with the corresponding rate for small- and mid-sized enterprises (SMEs) rising 0.17 percentage points to 2 percent.

The delinquency ratio of banks' household lending edged up 0. 04 percentage points on-month to 0.79 percent as of the end of November. The default rate for home-backed loans, which account for most of household loans, inched up 0.03 percentage points on- month to 0.69 percent in November, with the rate for other household loans such as credit lending gaining 0.05 percentage points to 0.98 percent.