SEOUL - South Korean banks' loan delinquency ratio jumped to the five-month high in October due to a surge in new delinquent loans from shipbuilders and builders, the financial watchdog said on Monday.

The rate of bad loans overdue for more than one day reached 1.28 percent of the total bank loans to companies and households as of the end of October, up 0.24 percentage points from a month earlier, according to the Financial Supervisory Service (FSS). The October figure was the highest since 1.3 percent tallied in May.

The October jump came after fresh delinquent loans held by firms in the shipbuilding, construction and real estate sectors grew sharply, according to the FSS. Seasonal factors contributed to the growth as local firms were reluctant to resolve overdue loans right after the quarter-end book closing.

New delinquent loans amounted to 3.7 trillion won ($3.28 billion) as of the end of October, up 1.9 trillion won from a month before, while overdue loans resolved reached 1.1 trillion won, down 2.5 trillion won from the previous month.

The delinquency ratio of banks' corporate lending came in at 1. 73 percent in October, up 0.4 percentage points from a month before. The default rate for large corporations climbed 0.86 percentage points on-month to reach 1.36 percent as of end-October, with the corresponding rate for small- and mid-sized firms gaining 0.27 percentage points to 1.83 percent.

The delinquency ratio of banks' household lending edged up 0.04 percentage points on-month to 0.75 percent as of the end of October. The default rate for home-backed loans, which account for most of household loans, inched up 0.03 percentage points on-month to 0.66 percent in October, with the rate for other household loans such as unsecured loans gaining 0.08 percentage points to 0.93 percent.