ATHENS, Greece (AP) — Greek authorities imposed a 14-day quarantine on an overcrowded migrant camp on the island of Lesbos Wednesday, after one man who had been living outside the official camp tested positive for the coronavirus.

The 40-year-old Somali is the first confirmed coronavirus case at the Moria camp, which as of Aug. 31 housed 12,714 people, several times its capacity of 2,757.

The Migration Ministry said the infected man was granted refugee status and a residence permit to live in Greece and had left the camp on July 17. However, he returned in recent days and had been living in a tent outside the camp fence. He is currently hospitalized in isolation on Lesbos.

The ministry said no entry or exit from the camp would be allowed until Sept. 15 and that the police presence would be increased around the camp to fully enforce the lockdown.

Only essential staff will be allowed to enter the camp after undergoing temperature checks.

Health authorities said the Somali man’s contacts were being traced and all would be quarantined, while extensive coronavirus tests were being conducted on the camp’s residents.

More than 27,000 migrants and asylum-seekers live in camps on the Greek islands, after arriving from the nearby Turkish coast. Moria, by far the largest of the camps, previously had been free of confirmed COVID-19 cases.

The International Rescue Committee aid group called for vulnerable people to be evacuated from Moria.

“Overcrowding and limited access to clean water and washing facilities have left tens of thousands of people across the Greek islands vulnerable and exposed to the virus,” the IRC said in a statement. “COVID-19 could spread rapidly and those at risk, including the elderly, pregnant women and those with underlying health conditions, must be urgently evacuated to safety before it is too late.”

Greece has been seeing a spike in coronavirus infections in recent weeks, which authorities have attributed to people on holiday ignoring protective measures such as maintaining social distance. The country was initially credited with tackling the pandemic's initial outbreak well, with an early lockdown keeping the number of seriously ill people and of deaths low.

Health authorities on Wednesday announced 233 new confirmed coronavirus cases and two new deaths in the previous 24 hours. Greece's total confirmed cases stand at 10,757, with 273 deaths.