Firefighters on Saturday placed under partial control a large forest fire that broke out on the northeastern outskirts of Athens, officials said.

"I believe we are going well," Pavlos Papageorgiou, a senior fire department officer, told state television NET.

"The only front is in a ravine near the town of Afidnes, we are moving forces from other areas where the fire is under control," he said.

The fire broke out before dawn near Afidnes, clouding the skies over the capital's northern suburbs with smoke and ash. It had earlier threatened an army camp and an industrial park in the vicinity.

NET said a number of homes and vehicles had been burnt in the community of Drosopigi and that local residents had heard explosions before the fire broke out, suggesting that arson was involved.

Traffic police briefly diverted traffic on the national highway leading north of Athens as a precaution.

The same area had also been ravaged by fires in 2009.

Greece suffers from a large number of summer fires usually aided by high temperatures and strong winds and are often attributed to arson.

The Athens national observatory this week said the months of June and July were among the hottest on record.

The worst disaster this season occurred on the Aegean island of Chios where scores of mastic orchards were destroyed by a fire burning for a week.

Earlier this month, another wildfire blazing for five days threatened Mount Athos, a UN World Heritage Site in northern Greece, that is home to the world's oldest surviving monastic community.