Greece's coast guard says three migrants or refugees who had been reported missing at sea overnight have been found alive and rescued by a fishing boat.

A search and rescue operation involving a helicopter, a coast guard patrol boat and a vessel from the European border patrol force Frontex was launched when the three were reported missing off the coast of the eastern Aegean island of Kos, the coast guard said Tuesday. It was unclear how they ended up in the water.

Greece has been overwhelmed by a massive refugee and migration crisis, with more than 200,000 people arriving so far this year. The coast guard said it had rescued 1,058 people at sea in 28 incidents off eastern Aegean islands from Tuesday morning to Wednesday morning.