A South Korean state-run economic institute on Tuesday downgraded its growth outlooks for 2018 and 2019 amid the flagging corporate investment.

The Korea Development Institute (KDI) revised down this year's growth forecast for the South Korean economy to 2.7 percent from 2.9 percent estimated six months earlier.

Next year's growth outlook was lowered to 2.6 percent from 2.7 percent expected six months ago.

The KDI's growth estimate for this year was identical to the figure, unveiled by the Bank of Korea (BOK) which cut this year's growth outlook from 2.9 percent to 2.7 percent in October.

The finance ministry set its growth forecast for this year at 2.9 percent.

The KDI said private consumption moderated amid the slumping corporate investment, noting that the expansion in the manufacturing and construction sectors slowed amid the moderating services industry.

Facility investment was forecast to reduce 1.8 percent this year, a downgrade from a 3.5 percent expansion estimated six months ago.

Outlook for the construction investment this year was cut to a 3.6 percent reduction from a fall of 0.2 percent.

Private consumption was expected to rise 2.8 percent this year, before growing 2.4 percent next year.

Export, which accounts for about half of the economy, was estimated to increase 8.7 percent in 2018, before gaining 4.6 percent in 2019.

The economic think tank said external uncertainties increased amid the expected rate hike in the United States and trade conflict among major economies.

The KDI set its outlook for consumer price inflation both in 2018 and 2019 at 1.6 percent.