At least 24 people, including children, have died after a boat carrying migrants sank off the north coast of Istanbul.

A search and rescue operation is taking place after a boat said to be carrying around 40 people sank near the Black Sea end of the Bosphorus strait.

Turkish broadcaster NTV said six people were rescued by coastguards, while 10 bodies have already been recovered.

Ali Saruhan, one of the rescuers involved in the search, told Hurriyet Daily News: "The wind is making our task very difficult. The boat is a very small one, it's in fact just a small boat. But they were carrying 40 people in it. We are seeing bodies of children floating in the sea."

More than 3,000 migrants died trying to cross the Mediterranean and Aegean so far this year, according to the International Organisation for Migration, but few have been reported to make it across the Bosphorus.