(Updates with details, environmental impact)
By George Hatzidakis
ATHENS, June 29 (Reuters) - The worst forest fires in more than a decade threatened Athens on Friday, with ash raining down on the Greek capital and thousands of firefighters, troops and volunteers battling a string of blazes around country.
Thick smoke hung over the Athens skyline, blocking out the summer sky. Grey-white ash covered cars and streets in a dusty film after the fires razed the last major forest near the city.
"This reminds me of the last day of Pompeii," said Natalia Giannaki, an Athens resident on her way to work, clasping a handkerchief to her mouth.
Thousands of firefighters, volunteers and more than 300 soldiers were drafted to fight the most serious fires on Mount Parnitha, about 25 km (16 miles) north of the city.
Police estimated more than 2,500 hectares (6,000 acres) of forest had been destroyed, including parts of the Parnitha National Park.
Smouldering trees and blackened hillsides were all that remained of the once lush, green hills that were considered the "lungs" of the city of more than 5 million people.
Citizens struggled with hoses and buckets of water to try to put out fires threatening their homes. An elderly woman wept at what she described as scenes of "biblical destruction".
"Parnitha was home to thousands of various flora and fauna, including the rare red deer. It was a very important ecological area," Dimitris Karavellas, head of WWF Hellas told reporters.
The fires were the worst to hit Athens since the five-day Mount Penteli blaze in July 1995. The mountain north of Athens, formerly covered by forest, has yet to recover fully.
Five other major fires in central and northern Greece were still raging but were nearly under control, fire services said. At least two people died near the central town of Agia after they were trapped in their car on Thursday.
More than 30 firefighters were taken to hospital because of smoke inhalation.
Fire brigade officials said many fires had been sparked by wooden pylons catching fire in a week-long heat wave that saw temperatures soar above 40 degrees Celsius (104 F), but in some cases they were investigating possible arson.
Some of the fires broke out at rubbish dumps, police said.
The main fire at Parnitha began 80 km (50 miles) north of Athens on Wednesday and quickly spread south. During the night the blaze swept through thick pine forests, moving closer to the northern suburbs of Menidi and Thrakomakedones.
The fire threatened the Mont Parnes casino hotel, Athens's only casino, which was evacuated on Thursday. But the fire made it too dangerous to use the funicular to bring everyone down the mountain and some die-hard gamblers refused to leave. (Additional reporting by Tatiana Frangou in Athens)