The accident occurred near the tiny Greek island of Oinousses.

A baby and a toddler were among seven people who died Friday when a migrant boat sank in the Aegean Sea, the Greek coastguard said, as rescuers searched for another four people missing.

The accident occurred near the tiny Greek island of Oinousses, located between the island of Chios and the Turkish coast.

Four children were rescued along with five men and three women, the coastguard said. Their nationalities were not immediately known.

Rescue crews initially recovered the bodies of a baby and a four-year-old child. But after survivors told authorities that four people on the boat were still missing, the bodies of three more children and two women were found.

"The five bodies will be taken to Chios to determine if these are the people the survivors were talking about," a coastguard spokeswoman told AFP.

Hundreds of migrants and refugees have died in recent years while attempting to cross the Aegean Sea in small, overloaded boats. Over 50 have died so far this year, according to the International Organization for Migration.

Greece is hosting some 70,000 mostly Syrian refugees and migrants who have fled their countries since 2015, and crossed over from neighbouring Turkey.

Under an agreement reached with the European Union in 2016, Turkey has made greater efforts to limit departures towards the five Greek islands closest to its shores.

But the number of arrivals has been steadily climbing in recent months.

Prime Minister Kyriakos Mitsotakis this week said some 3,000 people had arrived from Turkey in recent days, placing additional pressure on camp facilities on Greek islands that are already vastly overcrowded.