Tour operators were last night closely monitoring Greek forest fires that have already claimed 57 lives.

The Association of British Travel Agents (Abta) said its members only had a handful of holidaymakers in the areas most affected by the blazes.

Firms, however, are bracing themselves for action in case winds change and popular resorts are put at risk. Half the country has been affected but the worst fires are blazing in the dry forested hillsides of the Peloponnese region.

A spokesman for Abta said: "The Peloponnese, where the fires are raging at the moment, are not a popular destination for British tourists."

A fire that broke out yesterday on the island of Evia north of Athens killed five people and injured two more, while another person was killed by a separate fire in the south, the fire department said, bringing the death toll in the country's wildfires to at least 57.

Greek firefighters said there were 200 individual blazes and 42 fronts concentrated in the Peloponnese and Evia.

Arson has been blamed in several cases, and seven people have been detained. A reward of up to 1m euros (£680,000) was offered yesterday for information leading to the arrest of any arsonists.

"The reward is set between 100,000 to 1 million euros for every arson, depending on whether death or serious injury occurred and the size of the damage," the Public Order Ministry said in a statement.

New fires broke out yesterday in the region of Fthiotida - one of the few areas that had been unscathed. "Fires are burning in more than half the country," said fire department spokesman Nikos Diamandis. "This is definitely an unprecedented disaster for Greece."

His colleagues did, however, manage to save one of the country's most historic tourist landmarks. Fire had licked the outskirts of Olympia, birthplace of the Olympic Games.

"The fire reached the hill overlooking Olympia but was stopped just before entering the archeological site," said another spokesman. "Six planes, two helicopters, 15 fire engines and 45 firemen participated in the effort."

People had fled in panic from hotels and villages near the ancient site.

In the early morning, church bells rang out in Kolyri as residents gathered their belongings and fled through the night.

Fotis Hadzopoulos, a resident, said the evacuation was chaotic. "Children were crying, and their mothers were trying to comfort them," he said.

There were fears last night that the official death toll of 57 would rise as new fires broke out and winds pushed flames through villages and hamlets. Local media reported several people had been injured and killed by the fires yesterday but authorities could not immediately confirm the information.

Authorities evacuated hundreds trapped in villages, hotels and resorts. Soldiers, backed by military helicopters, reinforced firefighters stretched to the limit.

In the Peloponnese, rescue crews on Saturday picked through a grim aftermath that spoke of last-minute desperation as the fires closed in.

Dozens of charred bodies have been found across fields, on roads and in cars, including the remains of a mother hugging her four children.

At least 12 countries were sending reinforcements, and six water-dropping planes from France and Italy joined operations yesterday.

The worst affected region was around the town of Zaharo, south of Olympia. Smoke could be seen more than 60 miles away. The blaze broke out on Friday and quickly engulfed villages, trapping dozens of people and killing at least 37.

Scores of people were treated in hospitals for burns and breathing problems.