The Central Election Bureau said Monday, after centralizing data in 99.97% polling stations, that voter turnout at the referendum was 46.23%.
It said the results in 18,544 polling stations were centralized until 1:30 p.m., accounting for 99.97% of a total of 18,548 polling stations.
According to preliminary results, 87.52% of ballots were in favor of impeachment and 11.15% opposed.
The election bureau said the final results will be made public Wednesday.
The referendum required a voter turnout of more than 50% to be legally binding.