Korea's leading state think tank will likely revise down the country's growth estimate to below 3 percent for the year, following earlier downgrades by local and overseas institutions, a source said Sunday.

The Korea Development Institute (KDI) plans to unveil a revised version of its gross domestic product growth forecast for 2015 and 2016 on Nov. 23, according to the source who asked not to be named.

In its earlier outlook released on May 20, the KDI said Asia's fourth-largest economy will likely grow 3 percent this year and 3.1 percent next year.

However, the KDI is expected to reset the rate at below the 3 percent level for 2015, regarding a sharp drop in domestic consumption stemming from the spread of the Middle East Respiratory Syndrome (MERS) after June.

"The MERS impact will be reflected in the forecast revision," said the source. "(The South Korean economy) underperformed in the second quarter."

Last month, the International Monetary Fund (IMF) revised down the growth forecast of the 2015 South Korean economy to 2.7 percent from 3.1 percent predicted in May.

The IMF-projected growth rate for 2016 fell to 3.2 percent from 3.5 percent over the five-month period.

Local private think tanks also reported lower growth forecasts for the year, with LG Economic Research Institute suggesting a 2.6 percent gain and Hyundai Research Institute presenting 2.5 percent growth.

Consensus Economics, an international survey of economic forecasts by global investment banks and institutions, predicted that South Korea will expand an average 2.5 percent this year.

For next year, Consensus Economics estimated an average 2.9 percent expansion, while the KDI is expected to follow suit, according to the source. (Yonhap)