ATHENS — Greek authorities say they are searching for the captain of a small Polish-flagged sailboat found moored in a bay on the island of Salamina, near the country’s largest port of Piraeus, carrying five Syrian nationals who had been smuggled into the country from neighboring Turkey.

Greece is a major entry point into the European Union for people fleeing conflict or poverty in the Middle East, Asia and Africa. The vast majority attempt the brief but often dangerous crossing from the Turkish coast to nearby Greek islands, frequently in vastly overcrowded, unseaworthy dinghies.

But it is highly unusual for authorities to find migrants or asylum-seekers in boats that have reached Saronic Gulf islands like Salamina, which lies just a few miles (kilometers) off the coast of the Greek capital.

The five — two men, two women and a girl — were found on board the sailboat on Saturday night, the coast guard said Tuesday. They told authorities they had paid 4,000-5,000 euros each to be transported from the Turkish coast to another European country, via Greece. There was no further information available on what their final destination was to be.

The coast guard said one of the two women on board was transported to a local health center for medical treatment. It did not specify what treatment the woman needed.