Rescue department sources said three incidents of fire took place in Lappeenranta forest areas in the afternoon while another fire broke out in the nearby Luumäki forest.
Sources said 12 fire fighting units in Lappeenranta region brought the fires under control.
A total of 80 fire fighters and a Border Guard helicopter took part in the fire-extinguishing drive.
Finnish Meteorological Institute sources said the ongoing heat wave resulted in as many as 15 incidents of fire on Saturday.
The fires burnt 10-hector area in Kuopio Karttula while more than five hectors of forest was destroyed in Utajärvi.
Forest fires also broke out in different areas of Kolari, Kemiö Island, Taivalkoski and Hamina, the sources said.
