Greece announced the first coronavirus case in its largest migrant camp, the Moria Reception and Identification Center on the island of Lesvos, after a man who had been living outside the camp tested positive.
The camp has been placed under quarantine for two weeks.
The Migration Ministry said the infected man, a 40-year-old Somali, was granted refugee status and a residence permit to live in Greece. He had left the camp on July 17, however he returned in recent days and had been living in a tent outside the camp fence.
According to the latest data, Greece's overcrowded migrant camp on the island of Lesvos houses 12,714 people, several times its capacity of 2,757.
Tens of thousands of refugees and migrants, including thousands of unaccompanied children, are living in squalid conditions in overcrowded camps on several Greek islands after arriving from the nearby Turkish coast.
"Today's confirmed incident points out the need to create closed-type and controlled facilities," said Migration and Asylum Minister Notis Mitarach.
The shutting down of Moria is "a development in progress that will enhance the sense of safety - in health and other areas - for both the residents and local communities," the minister added.
Police presence will be increased around the camp to enforce the lockdown which is in place until September 15.
"From the first minute, we took all the necessary measures for the health protection of the reception facilities. We are dealing with the issues of public health in cooperation with the National Public Health Organisation and the Civil Protection general secretariat," he concluded.
Only essential staff will be allowed to enter the camp after undergoing temperature checks.
The Somali man is isolated in hospital and is in good health. His contacts are now being traced and "extensive checks" are underway at the camp.
It is recalled last week restrictive Covid-19 measures were imposed on Lesvos. They ended on September 1.