252 of them have been arrested for fires caused by negligence and 29 for arson, the Greek fire service said.
The Greek government has in recent years tightened penalties for people convicted of causing fires. They now face prison sentences of up to 20 years and fines of up to 200,000 euros.
Greece remained on high alert for wildfires on Wednesday, just days after a fire destroyed more than 11,000 hectares of pine forest, shrubland and farmland near a seaside resort northwest of the capital Athens.
On Wednesday, a 59-year-old man was arrested in Thessaloniki in northern Greece for his involvement in more than five fires over a two-week period.
