Greek authorities have arrested two men for trying to smuggle a group of migrants to Italy, 12 of whom died when their boat capsized, the coastguard said Saturday. A 58-year-old foreign national -- the captain of the inflatable boat that sank off the western Greek island of Lefkada early on Friday -- was arrested along with a 20-year-old Greek, according to an official statement. Fifteen other passengers survived the tragedy in the Ionian Sea and managed to alert the authorities. Four of the dead were the children. "The 58-year-old appears to have set up a criminal organisation for the illegal smuggling of migrants from Greece to Italy, along with four Greeks (three men and a woman) and another foreign national," the coastguard said. Authorities are still searching for the other suspects and have also seized two cars they believe were used in the smuggling operation. The nationalities of the 27 migrants, who were travelling in an eight-meter (26-foot) inflatable dinghy, are not known. Greece is one of the main ports of entry into the European Union for migrants and refugees fleeing war-torn and impoverished countries in Africa, the Middle East and the Indian subcontinent. Refugee traffic has soared over the past year because of the ongoing war in Syria. Arrivals by sea have increased owing to stricter controls on the Greek-Turkish northern land border. Europe's immigration policies have come under the spotlight after more than 400 asylum seekers drowned in October in two tragedies near another popular migrant port of entry, the Italian island of Lampedusa.