Parts of Athens have been evacuated after more than 50 wildfires broke out in 24 hours, fuelled by dry conditions, high winds and extreme temperatures.
People living in the suburb of Kryoneri, around 12.5 miles (20 km) northeast of the Greek capital, were told to move to safe areas on Saturday.
At least five people, most of them elderly with respiratory problems, have been treated in hospital for burns or smoke inhalation.
Almost 150 firefighters are battling the blaze, backed up by 44 fire engines, 10 firefighting planes and seven helicopters.
Greece has asked for six firefighting planes from the European Union's Civil Protection Mechanism to help fight the 52 wildfires raging this weekend, fire service spokesman Vassilis Vathrakoyannis said.
Photos showed houses and tree-covered hills on fire as temperatures hit 38C (100F) - with warnings they could climb to 44C (111F) - and dry conditions and high winds fanned the flames.
Mr Vathrakoyannis said that under such conditions wildfires "expand very quickly and become dangerous", adding: "These conditions are expected to prevail over the coming days."
There have been reports of damage, he said, and authorities "will take stock when the fires have been put out".
At least 335 firefighters are battling three major fires in the southwest on Greece's two largest islands - Crete in the south and Evia north of Athens - and also on the island of Kythera, northwest of Crete.
Helping in the effort to extinguish them are 19 planes and 13 helicopters, but they can only operate in daylight, the spokesman said.
Wildfires, many of them destructive, have become a common occurrence in Greece in recent years and several have broken out in the past month.
In neighbouring Albania, 26 fires broke out throughout the country on Saturday, following a large fire near the southern Albanian town of Delvina on Friday, which injured three people and forced the evacuation of about 2,000 residents.
In Kosovo, firefighters managed to extinguish 17 blazes fuelled by strong winds while 12 others remained active, officials said.
Eight cows were killed in the southern town of Prizren, after a fire engulfed a farm, local emergency services said while 40 sheep died in a fire in the east of the country.
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In Turkey, the country's fourth-largest city, Bursa, was threatened by wildfires that have been burning for weeks, local officials said on Sunday.
More than 1,100 firefighters are trying to put the blazes out and nearly 1,800 people moved to safe areas from nearby villages.