Greek authorities on Tuesday relocated dozens of migrants from a congested camp on the island of Lesbos following three deaths attributed to carbon monoxide poisoning.
State agency ANA said around 150 people were moved out of the camp of Moria, and work is underway to improve facilities for others still sleeping in tents.
"There are currently around 250 migrants in single-person tents. At the end of the week we aim to have none," immigration ministry official Anthee Karangeli told ANA.
Some 50 migrants were relocated to a Greek navy ship moored at the local port and another 100 were moved to a second camp on the island where conditions are better, the agency said.
Immigration minister Yiannis Mouzalas on Monday told reporters in Athens that additional heated tents would be installed in Moria.
The moves came after three men died in the camp in the space of six days, and a fourth was hospitalised.
The four men from Pakistan, Egypt and Syria were sharing two tents.
Greek media have cited carbon monoxide poisoning as a possible cause of death, as the cold weather has forced migrants to use makeshift stoves in tents pitched outside to keep warm.
Coroners have not announced the definitive results on what caused the three deaths, but a police source told AFP that the deaths were probably not drugs-related.
The UN refugee agency, which helps the Greek government manage the camps, declined to comment.
In November, a 66-year-old Iraqi Kurd and her six-year-old grandson died in Moria from the apparent explosion of a cooking gas cannister inside their tent.
The boy's mother and four-year-old sibling also suffered serious burns.
Greece has over 60,000 refugees and migrants on its soil, the result of a series of border closures in the Balkans and eastern Europe last year.
Many of the camps are overcrowded, especially on the islands facing Turkey. On Lesbos there are nearly 5,000 people in camps nominally built to hold 3,500, according to government figures.
The Greek immigration ministry has refused to permit large-scale relocation from the islands to the mainland, fearing that such a move could jeopardise an EU-Turkey agreement that has helped stop further arrivals to the continent.
There are frequent clashes in the island camps, with the residents tired of the long wait for asylum papers and fearful of being returned to Turkey.