ATHENS: Fire crews outside Athens scrambled Monday to exploit a lull in high winds, but the flames spread further and a dozen nuns had to be rescued from a convent threatened by one blaze.

Six major fires were burning Monday across Greece, including blazes on the islands of Evia and Skyros in the Aegean Sea and Zakynthos in the west. But the most dangerous was the fire near Athens, which started north of the Marathon plain and spread over Mount Penteli on the northern edge of the Greek capital.

The massive wildfires broke out Friday and have razed about 58 square miles (37,000 acres or 15,000 hectares) of forest and brush, damaged or destroyed scores of homes and forced thousands to flee outlying areas of Athens.

At first light Monday, 17 water-dropping planes and helicopters swooped over flames near populated areas, trying to knock down the fire before the stronger winds expected later in the day.

At least five people were being treated for burns and several dozen had reported breathing problems, but no injuries were serious, Health Ministry officials said.

"There are some signs of optimism but no letting up of the firefighting effort. We have a chance to contain this nightmare that has burned the city's main forest area," Athens regional governor Yiannis Sgouros said. "After this, we will assess the extent of this catastrophe — how many homes were destroyed, and how much damage was done."

Prime Minister Costas Karamanlis toured the affected area on Sunday, amid criticism of his government's response to the emergency. The mayor of Marathon, Spyros Zagaris, was among several local leaders who accused the government of having no coherent plan to fight the fire.

The Greek government also faced severe criticism for its fire-fighting abilities in 2007, when fires ravaged southern areas of the country, killing 76 people.

Thousands of people fled the fire-striken areas over the weekend, many on foot because fires closed nearby roads. But government spokesman Evangelos Antonaros said the number of people involved in state-organized evacuations was "limited" and most have now returned to their homes.

Antonaros on Monday defended the government's response.

"A massive effort is underway to contain these fires," Antonaros said. "From the first moment, (we had) the presence of personnel on a large scale."

Up to 2,000 firefighters, soldiers and volunteers are involved in fighting fires stretching more than 30 miles (50 kilometers) northeast of Athens. Aircraft have been sent from France, Italy and Cyprus, with more help expected from other countries.

Fires raged, meanwhile, at the coastal town of Nea Makri and nearby Marathon — site of one of ancient history's most famous battlegrounds — to the northeast of the capital, and at Vilia to the northwest.

At Nea Makri, a blaze was tearing down a hillside toward houses, and a dozen nuns were rescued from a nearby Christian Orthodox convent threatened by fire. Volunteers, clutching branches and with water-soaked towels wrapped around their necks, beat back the flames as the evacuation took place.

Elsewhere, residents defended homes, soaking their front yards with garden hoses and buckets of water.

Fires continued to threaten the ancient fortress town of Rhamnus, home to two 2,500-year-old temples.

Over the weekend, authorities evacuated two large children's hospitals as well as campsites and villages in an outlying suburb of the capital.

Officials have not said what started the fires — the worst since 2007. Hundreds of forest blazes plague Greece every summer and many are set intentionally — often by unscrupulous land developers or animal farmers seeking to expand their grazing land.