A total of 477 road accidents were reported on Wednesday, the first day of the so-called seven dangerous days of Songkran, killing 39 people and injuring 461 others, the Road Safety Centre announced.
Tourism and Sports Minister Weerasak Kowsurat told the media at the centre that an estimated 40 per cent of the accidents were caused by drink driving.
He said around 82 per cent involved motorcycles with long, straight, major roads more likely to see crashes.
Most accidents happened from 4pm to 8pm, the minister added.
Chiang Rai came top with 18 accidents.