The ministry also lowered its 2019 export growth forecast to 3.4 percent from 4.5 percent, Lavaron Sangsnit, head of the ministry's fiscal policy office, told a briefing.

The revised forecasts do not take into account measures planned to bolster the economy, which are expected to add 0.1 percentage point to growth, he said.

"Growth is slowing and that's why we will have economic measures, which should be submitted to the cabinet tomorrow," he said.

Earlier this month, Finance Minister Apisak Tantivorawong said the ministry would introduce measures worth about 20 billion baht ($626.76 million) to spur economic growth, which was expected to slow to about 3 percent in the first quarter from a year earlier.

Official first quarter gross domestic product (GDP) will be released on May 21.

Annual growth in the first half of 2019 is projected at 3 percent and at 4.5-4.6 percent in the second half, Lavaron said.

Southeast Asia's second-largest economy expanded 4.1 percent in 2018, the fastest pace in six years.

The ministry also predicts the benchmark interest rate  will remain unchanged at 1.75 percent throughout this year, Lavaron said.