ATHENS (Reuters) - Indebted Greece is set to face a cost of more than half a billion euros this year to handle the migrant crisis, a central bank source said on Thursday, with the bill likely to increase if the situation worsens.

“It’s a conservative‎ estimate, costs could go up if there is increased inflow and refugees become logjammed in Greece due to border closures,” the Bank of Greece source said.

The estimate, which included search and rescue operations, infrastructure, and repatriation costs was 600 million euros, the source said.

Greece, a gateway for hundreds of thousands of refugees and migrants fleeing upheaval in the Middle East and beyond in 2015, has reacted with growing alarm to a progressive closure of borders along a Balkan corridor to its north, raising the prospect of migrants being trapped in the country.