The fire at Moria refugee camp on Lesbos was started by asylum seekers, Greek Migration Minister Notis Mitarachi said, as quoted by AFP.
"Many fires broke out in the camp overnight from Tuesday to Wednesday... the incidents in Moria began with the asylum-seekers because of the quarantine imposed" after 35 cases of coronavirus were detected in the camp, Mitarachi said, according to the agency.
No-one was seriously injured in the fire, he added.
Earlier in the day, Greek Prime Minister Kyriakos Mitsotakis called an emergency cabinet meeting following the devastating fire in the largest migrant camp on the island.
Moria accommodated over 12,000 people, which is more than four times the number it can officially have. Thousands of refugees have been forced to flee the site after the fire.