Turkish media say 22 people, including four children, have drowned after a 20-meter wooden boat sank off Turkey's coast.

The private Dogan agency said 211 people were rescued from Tuesday's sinking in international waters between Datca in Turkey and the Greek island of Kos. It wasn't immediately clear where the people were from, or what caused the sinking.

The incident comes two days after 34 people, including 15 children, drowned off the Greek island of Farmakonissi when the wooden boat they were on sank. Nearly 100 other people were rescued.

More than 250,000 people have entered Greece so far this year in an attempt to reach the more prosperous northern European countries. The vast majority are Syrian refugees making the perilous sea crossing from the nearby Turkish coast.