Some who fled the fires on Tuesday and Wednesday night tested positive for COVID-19 after an outbreak of the disease in the camp, further complicating attempts to round up migrants and get them into alternative accommodation.
"Today we will undertake all necessary actions to house families and the vulnerable while food distribution continues," government spokesman Stelios Petsas told reporters.
Bracing for a possible surge in COVID-19 cases, authorities were sending 19,000 test kits to the island. Petsas added that a passenger ferry had docked at the island's port of Mytilene to house families.
Petsas said Tuesday's fire, which reduced the Moria camp holding some 12,500 people to a mass of smouldering steel and melted tent tarpaulin, was started by asylum seekers reacting to quarantine measures after COVID-19 infections were detected. He did not provide evidence.
"Some do not respect the country hosting them. They take advantage of any excuse to set every solution on fire," he said.
The camp was quarantined last week after its first COVID-19 case surfaced. Until the fire broke out, 35 migrants had tested positive and most of them were moved into an isolation unit in the camp. After the blaze erupted and the camp was evacuated, only eight of them had been tracked down.
On Thursday, Migration Minister Notis Mitarachi said all of them were missing again.
"The health issue is very important, that's why we need to have a new temporary accommodation soon," he told MEGA TV.
Earlier, authorities moved 406 unaccompanied children and teenagers from the camp and its poor living conditions to the mainland. But thousands more people remained stuck in Lesbos with nowhere to sleep and little to eat.
Local attitudes toward the migrants, on an island at the forefront of the European migrant crisis in 2015-2016, have turned largely hostile in recent years as the number of people in the camp gradually increased.
Families slept on roadsides and in fields across the island overnight after a second fire broke out at the camp late on Wednesday, destroying what was left from the first inferno.
On a parking lot outside a supermarket, more than 1,000 migrants, including families with small children, waited in the sunshine for bottled water and food to be distributed.
SPARE A BISCUIT?
The 406 unaccompanied minors were taken to safe facilities in northern Greece where they will stay temporarily, while preparations for their relocation to other EU countries is ongoing.
Valencia, an eight-year-old Congolese girl who was barefoot, gestured to a Reuters reporter that she was hungry and asked for a biscuit.
"Our home burned, my shoes burned, we don't have food, no water," she said.
Both she and her mother, Natzy Malala, 30, who has a newborn infant, slept on the side of the road.
"There is no food, no milk for the baby," Natzy Malala said.
Government plans to find shelter for the migrants were likely to be met with resistance. Authorities were already at loggerheads with Lesbos residents over plans to replace Moria with a closed reception centre, which the residents fear would mean thousands of asylum seekers remaining their permanently.
Municipalities were at odds over the situation, said Costas Moutzouris, governor of the Northern Aegean.
"There is no decision. It's up in the air," he told Reuters.Another government official, who declined to be named, said sheltering migrants on boats was not a safe solution.