Details about the incident, which occurred on Monday morning near where the Black Sea and the Bosphorus Strait meet remain sketchy.

Turkish media and news agencies have reported that at least 24 people died when the boat they were traveling in capsized. At least seven people are reported to have been rescued, with some sources putting the number of people saved to be as high as nine.

It was not immediately clear what caused the vessel to capsize. The Associated Press cited a senior officer with the Turkish military's general staff in Ankara, who said the victims were believed to be from Afghanistan and Syria. Colonel Sakir Cicek said it wasn't clear from where the boat had set sail.

Coast guard officials said that seven boats an a helicopter were continuing search operations in the area. Some local media reported that around 40 would-be migrants were on the vessel when it sank.

Many people fleeing places such as Syria or Afghanistan pass through Turkey as they try to reach the EU. With the bloc's southern outer borders having become more difficult to penetrate, an increasing number of migrants have been trying to reach Europe by attempting to cross the Mediterranean in unseaworthy vessels.

pfd/mkg (AFP, AP, dpa)