Fires that have claimed 20 lives in Greece are still burning out of control in foothills near Athens and the Evros region near the border with Turkey.

Eighteen of those killed are thought to be refugees and migrants who crossed the border recently, hiding in forests north of the city of Alexandroupolis.

Greece has expressed its deepest sorrow for the deaths in the Dadia forest close to the Turkish border.

For five days, fires have burned near the city and west along the coast.

Firefighters are also trying to stop a fire spreading from the slopes of Mount Parnitha, to the north-west of Athens.

Their efforts are being hindered by strong winds whipping up the flames and searing heat of up to 40C (104F).

The 18 bodies were found on Tuesday by the fire service near a shack outside the village of Avantas, to the north of Alexandroupolis.

“Unfortunately, their stay in the Dadia forest proved fatal,” said government spokesman Pavlos Marinakis, pointing out that the alarm had been raised in the area where they were found and evacuation messages had been sent on the mobile 112 emergency service.

Migrants and refugees trying to reach the European Union face many perils – being beaten, robbed, arrested, forced back across a border, or drowning in the Mediterranean. Now the risks also include a ring of fire in northern Greece.

Fire service spokesman Yiannis Artopios said there had been no reports of missing residents and it is widely assumed those who died had recently crossed Greece’s long, snaking border with Turkey along the River Evros.

For many who are desperate to reach EU soil, the river is their gateway and the vast forest on the other side provides cover.

All the dead were male, and two were minors according to local coroner Pavlos Pavlidis, who said the bodies were found within a 500m (1,640ft) radius, some near a sheep pen.

Their bodies have been taken to Alexandroupolis for post mortem examination. But identifying them will be difficult and authorities will need relatives to come forward.

One Syrian man has told the BBC he fears his 27-year-old cousin died in the blaze as he has been unable to reach him for four days. The cousin was among a group of Syrians, Afghans and Iraqis hoping to follow a well-worn path through the forest.

The Syrian said they would not have called Greek authorities for help, despite the evacuation order, for fear of being sent back across the border to Turkey.

Greek police say throughout August as many as 900 people a day have tried to sneak across the border, and hundreds of traffickers have been arrested. People smuggling is big business, involving criminal networks.

Overnight at the Ipsala border crossing between Turkey and Greece, a group of young men tried to climb on to a lorry waiting to enter Greece.

One managed to conceal himself by lying flat on the top. The others melted away into the darkness when they were spotted.

Many residents in the villages around Alexandroupolis are furious, as they believe the fires are caused by migrants who cross the border and hide in the forest before heading inland.

There is no evidence, though, that this fire in the Dadia forest was caused by migrants.

A video filmed in the Alexandroupolis area has provoked uproar in Greece after it showed a man “arresting” refugees and migrants and locking them in a trailer attached to his car. The man walks around the trailer, accusing migrants and refugees of trying to burn Greeks. He then opens the door showing several frightened young men.

Police said it had arrested the man behind the video along with two people suspected of helping him. They added that the video had involved the illegal detention of “13 illegal immigrants of Syrian and Pakistani origin”.

In a separate development, Supreme Court Prosecutor Georgia Adeilini has called for a dual inquiry into the causes of the fires in the Evros region and into alleged incidents of racist violence against migrants that have followed the 18 deaths in the Dadia forest.

As the flames drew closer to Alexandroupolis, villages to the west and north of city were evacuated and dozens of patients from the university hospital were moved to a ferry berthed at the port.

Fires are still burning in the Dadia forest but the biggest front in the region is now to the west of Alexandroupolis.

The situation on the outskirts of Athens is proving increasingly difficult for firefighters and three nursing homes have been evacuated from the town of Menidi.

Homes have already burned Hasia and Fyli, in the foothills of Mount Parnitha.

Greek officials have called for the evacuation of thousands of people from the big district of Ano Liosia in the north-west of the capital, although many have refused to leave.