(Adds official's comments, details)
* Debt-to-disposable income ratio falls as income grows fast
* Household debt burden at one of highest in world
* Government struggling to contain debt growth
By Christine Kim
SEOUL, Dec 21 (Reuters) - Debt burden at South Korean households eased this year as income grew faster than debt, an official survey found on Friday, giving some relief to policymakers fighting slowing growth in Asia's fourth-largest economy.
Total debt at South Korean households grew by 1.7 percent on average to 52.91 million won ($49,200) by March 2012 over a year earlier, whereas annual disposable income grew 5.8 percent in 2011, the joint survey between the central bank and two top local authorities found.
As a result, the ratio of debt to disposable income decreased to 152.3 percent in the 2012 survey from 158.5 percent last year, the Bank of Korea said in a statement. The ratio is still one of the highest in the world.
"The pressure has eased on households as their debt hasn't changed much in the past year but household income has comparatively," said an official at the Bank of Korea.
Investors and credit rating agencies have cited the high ratio of debt to disposable income, a key measure of soundness in the household sector, as a major risk to South Korea at a time when the export-reliant economy is losing momentum.
The government's policy of encouraging establishment of small businesses on easy credit during the early 2000s and a domestic property boom later have both contributed to a jump in household debt over the period.
Alarmed by the fast deleveraging in the U.S. household sector and its impact on the economy during the 2008-2009 crisis, South Korean authorities imposed a set of measures in June 2011 to contain its household-sector debt.
Apart from the huge amount of consumer debt, banks' heavy dependence on overseas borrowing due to low domestic private savings has also left South Korea's banking sector as a whole extremely vulnerable to global credit market conditions.
The loan-to-deposit ratio at South Korean banks stood at as high as 122 percent in late 2007 but has since fallen to the mid-90 percent range thanks to efforts by the authorities to contain the debt problems, official data shows.
The latest survey added a section on spending patterns and doubled the survey sample to 20,000 households.
The expanded survey showed that although robust income growth lowered South Korean households' debt burden, they still feel pressured by their borrowings, with 68.1 percent of the respondents worried about paying back debt principal. ($1 = 1074.6750 Korean won) (Editing by Choonsik Yoo)