"A delayed economic recovery in major advanced economies will likely crimp Korea's exports and volatile financial markets will dent households' room for spending," the KIF said.

The think tank's growth projection was lower than the government's forecast of a 4.5 percent expansion. The central bank's 2011 growth estimate stood at 4.3 percent.

Global economic situations are growing bleaker, raising concerns that the global economy may slide back into a recession, hit by the first-ever U.S. credit downgrade and lingering eurozone sovereign risks.

South Korea's exports, which account for about 50 percent of its economic output, are expected to grow 9.6 percent in the second half after expanding 13.3 percent in the first half.

Even amid strong economic growth in emerging markets, sputtering growth in advanced economies will curtail demand for Korean products, causing the annual growth of Korean exports to reach 11.3 percent this year. Last year, overseas shipments expanded 15.8 percent.

Recent trade data also fanned concerns about the slowing economy. South Korea's trade surplus shrank to US$821 million in August as record high imports overshadowed export gains.

The KIF, meanwhile, expected South Korea's consumer prices to grow 4.2 percent this year due to rising food prices and a hike in public utilities charges that are hovering above the 2011 economic growth rate.

"But if the global economic slowdown or financial market jitters cause oil prices to sharply fall, there is a chance that the growth of inflation may be capped," the KIF said.

The government and the Bank of Korea expected consumer prices to grow 4 percent this year, due to higher oil and food prices.

Korea's consumer prices rose a jaw-dropping 5.3 percent in August from a year earlier, the fastest in three years. Consumer inflation surpassed the BOK's upper ceiling of a 2-4 percent band for the eight straight month in August.

The think tank said that if the U.S. economy falls into a double-dip recession and the eurozone debt crisis eventually cripples its financial system, the growth of the Korean economy may fall to around the upper range of 3 percent in the worst-case scenario.