Prime Minister Costas Karamanlis ordered that thousands of hectares of forestland destroyed by wildfires across Greece would be replanted.
Since Wednesday, fires have destroyed more than 6,000 hectares (15,000 acres) of forests left tinder-dry by a weeklong heat wave that reached the mid-40s degrees Celsius (up to 114 Fahrenheit).
Two people died in one fire, while 12 heatstroke deaths were recorded.
A volunteer firefighter collapsed and died while trying to extinguish a small brush fire outside a factory in the northern Athens suburb of Halandri on Sunday. Fire officials said the 26-year-old man fainted, apparently after inhaling smoke, and died on the way to hospital.
Arsonists seeking to clear prime land for development are suspected of causing some of the blazes.
"I stress most emphatically that all burnt forests are automatically scheduled for reforestation," Karamanlis said. "Wherever forests stood, there will be forests once again."
Temperatures were mostly under 30 Celsius (86 Fahrenheit) on Sunday.
About 150 firefighters, assisted by 300 army conscripts and water-dropping aircraft, fought Sunday to extinguish a large blaze that has destroyed at least 2,500 hectares (6,200 acres) of pine and fir in the Mount Parnitha national park, on the northwestern fringes of Athens, over the past four days.
Fire officials said the blaze had been contained to three main spots in the 26,000-hectare (64,000-acre) park that hosts more than 1,000 wildlife species, including a protected species of deer.
"The scar left behind by the fire on Mount Parnitha is a scar on our soul," Karamanlis said. "We must all work to make the forest as it was before."
President Karolos Papoulias said the Parnitha blaze cost the greater Athens region its only remaining major green area - "in other words, its hope."
Authorities said an incendiary device was found on Mount Parnitha. On the southern island of Poros, police on Saturday arrested a 20-year-old man suspected of lighting fires in the area.
Firefighters managed Sunday to partially contain fires on Mount Pelion in central Greece, Halkidiki in the north and on the Aegean Sea island of Lesvos, while three more blazes was burning in Crete and southern Greece.