South Korea's economy grew at a slower-than-expected rate in the third quarter of the year amid softening export growth, central bank data showed on Thursday, upping the possibility that the Bank of Korea may conduct another rate cut earlier than expected after its first rate reduction in over three years this month.

The country's real gross domestic product -- a key measure of economic growth -- gained 0.1 percent on-quarter in the July-September period, according to preliminary data from the Bank of Korea (BOK).

The third-quarter figure is sharply lower than the market expectation of a 0.5 per cent gain, and compares with the 0.2 per cent on-quarter contraction in the April-June period and the 1.3 per cent advance in the first quarter of the year, reports Yonhap news agency.

On a yearly basis, South Korea's economy grew 1.5 per cent in the third quarter, slowing from 2.3 per cent growth for the second quarter of the year.

Private spending rose 0.5 per cent on-quarter in the third quarter, recovering from a 0.2 per cent on-quarter dip the previous quarter, the central bank said.

The country's exports contracted 0.4 per cent in the third quarter, compared with the 1.2 per cent gain the previous quarter, while imports rose 1.5 percent in the July-September period, down from a 1.6 per cent advance the previous quarter.

Government spending gained 0.6 per cent, and construction investment went down 2.8 per cent in the third quarter, further contracting from the previous quarter's 1.7 per cent fall, according to the data.

The country may miss the central bank's growth estimate for the year given current trends, a BOK official said, with adjustments for growth and others to be assessed in November.

"Domestic demand has rebounded, but exports slowed sharper than expected," the official said, adding that robust exports may continue down the road.

For the whole year, the bank expects the economy to rebound slightly, at 2.4 percent.

To meet the central bank's forecast, the economy has to grow 1.2 percent on-quarter under the current quarter.

But with the slowing growth in IT exports and geopolitical tensions adding more uncertainties to overseas demand, it may be highly unlikely for Asia's fourth-largest economy to grow as expected this year, according to the BOK official.

Earlier this month, the BOK cut its key interest rate by a quarter percentage point to 3.25 percent, ending its yearslong restrictive policy amid moderating inflation and faltering domestic demand.