South Korea's major banks saw their capital adequacy ratios and earnings plunge in the third quarter due to tumbling housing market and mounting household debts, Korea Herald reported today.

Kookmin Bank announced its Bank for International Settlements (BIS) capital adequacy ratio has fallen below 10 percent for the first time since 2002.

In July-September period the BIS capital ratio of Kookmin bank stood at 9.76 percent, down from 12.45 percent in the second quarter.

The nation's largest lender by asset said its third-quarter net profit also dropped 28.6 percent to 553.3 billion won (US$418 million) from a year earlier.

Shinhan Bank, the nation's No. 3 lender, reported a BIS capitalratio of 11.9 percent in the third quarter, down from 12.5 percent from the previous quarter.

Its net profit dipped 32.2 percent to 214.3 billion won (US$162.3 million) in the third quarter from a year earlier.

The BIS capital ratio of Korea Exchange Bank and Industrial Bank of Korea also dropped to 10.64 percent from 11.56 percent and10.15 percent from 10.49 percent respectively during the same period.

The Korea Herald said the increase of asset risk of major South Korean banks mainly stems from higher competition for expansion and rising loans related to builders and property development.

It added that this could add greater burden on the nation's economy, which is currently showing signs of deterioration amid the ongoing global credit crunch.