Greek authorities have picked up more than 120 migrants who illegally entered the country by sea on three separate vessels, a day after a yacht with 90 people on board foundered just off the island of Rhodes, drowning three.

The Merchant Marine Ministry says 42 people, including seven children, were taken off a small boat near the eastern Aegean Sea islet of Agathonissi. All are in good health.

A further 84 people were located in separate incidents earlier Tuesday on the islet of Farmakonissi and the island of Lesvos.

About 550 migrants have reached Greek shores over the past three days, amid a surge of illegal immigration that has seen arrivals exceed 12,000 so far this year — a nearly threefold increase over 2014.