Tsipras told ministers at a cabinet meeting on Friday that he was conflicted over whether the authorities had done everything right in response to one of the worst Greek disasters in living memory, which killed at least 87 people, including children, east of the capital, Athens.
“I have called you here today first of all to take full political responsibility for this tragedy in front of my cabinet and the Greek people,” he said.
“I won’t hide that I am overwhelmed by mixed feelings right now … Pain, devastation for the human lives unexpectedly and unfairly lost. But also anguish at whether we acted correctly in everything we did,” Tsipras added.
The conservative party said questions were raised over the number of firefighters available and evacuation procedures.
Fofi Gennimata, of the opposition Socialist party, called for the government to resign over the disaster.
“This government is dangerous and must go,” Gennimata said.
Amid public anger over the government’s handling of the aftermath, Toskas said that “a serious piece of information has led to us opening an investigation” into possible “criminal acts”.
“Officials looking into the causes of the fires now believe that there are serious indications of arson,” said Al Jazeera’s Neave Barker, reporting from Mati.
“This had been the authorities’ early suspicion given the speed of the fires that sprung up both east and west of Athens, and also because they appear to have been started simultaneously.”
Barker added that the layout of Mati has also been blamed for making the situation much worse.
“Many of the houses here sprung up in the 1970s, 1980s and 1990s with no consideration for escape routes, particularly down to the beach.”
Rafina Mayor Evangelos Bournous said an evacuation would not have been an option, given the speed at which the fire spread and the haphazard layout of the area, which featured small winding roads and cliffs next to the sea.
“They speak of an evacuation plan. How can an evacuation plan be implemented on a settlement [built] outside of town planning, which does not have places for people to gather?” Bournous said.
“The evacuation plan was that everyone tried to leave altogether and they got trapped on the coastal road,” he said.
The government has announced a long list of relief measures including a one-off 10,000-euro payment for families of the victims.
About 300 firefighters and volunteers were still combing the area on Friday for those still missing. More than 500 homes were destroyed by the blaze.
Tsipras promised a national plan to tackle decades of unauthorised construction and to reform and upgrade the Civil Protection Service “to guarantee … that there will be no more tragedies”.
The disaster unleashed a wave of solidarity and many survivors were being looked after by voluntary organisations, who were providing them with accommodation, clothing and food.