Greece has “serious indications” that the fires that claimed the lives of at least 83 people in the resort town of Mati near Athens this week were deliberately lit.

Citizen Protection Minister Nikos Toskas told a media conference on Friday morning (AEST) that satellite image analysis and ground inspections suggested the blaze that broke out in multiple places over a short period of time likely resulted from arson.

“We have serious indications and significant findings of criminal activity concerning arson,” Mr Toskas said.

“We are troubled by many factors, and there have been physical findings that are the subject of an investigation.”

He declined to provide more details.

Some 60 people are still being treated in hospital, 11 in intensive care, with dozens more missing from the fire that broke out on Tuesday morning.

The death toll continues to rise as searchers uncover more victims from the smoke and flames.

Many of the survivors were saved by the sea, but dozens of victims were unable to reach the water, with many later discovered close to the cliffs overlooking the sea.

Mr Toskas’ claims come as Greek Defence Minister Panos Kammenos told the BBC that illegal construction had contributed to the disaster, while angry survivors demanded to know why no evacuation order was issued before the inferno.

Mr Kammenos said building by residents between wooded areas was a “crime” that had resulted in blocking escape routes.

He was confronted by angry locals as he visited areas devastated by the fires east of Athens.

“This shouldn’t have happened, people perished for no reason,” a tearful woman shouted Mr Kammenos as he visited Mati and nearby fire-ravaged areas.

“You left us at God’s mercy!”

It was unclear why there was no evacuation order, with the fire brigade, local administration and central government each saying the other was responsible.

With the death toll expected to rise further, about 300 firemen and volunteers combed the area for dozens still missing.

One woman was looking for her brother, who had been returning from work when the flames took hold. “My father was the last person to talk to him on Monday evening,” Katerina Hamilothori told Skai TV. “We have had no news at all.”

Outside the coroner’s service in Athens, the mood was grim as relatives of victims arrived to submit information and blood samples which could assist identifications.

“This is a difficult process, more difficult than other mass disasters we have dealt with,” coroner Nikolaos Kalogrias said, adding that the bodies of most of the victims were completely charred.

About 500 homes were destroyed in the fires, and the fire brigade said there were closed-up homes that had not yet been checked.

The government announced a long list of relief measures including a one-off payment and a job in the public sector for victims’ spouses and near relatives.

But for many, that was not enough to ease the pain.

-with agencies