Lesbos migrant: 'I lost my son when dinghy was hit'
Hundreds of migrants have died or gone missing at sea, and tens of thousands have had to be rescued, as they attempt to cross from the Turkish coast to the Greek islands.
Already this year, nearly 200,000 have passed through the Greek island of Lesbos.
The Greek authorities are investigating allegations by one group of survivors that people on a boat that struck their dinghy saw it cut in half but sailed on.
Jim Muir reports from Lesbos, where one man is hoping for news of his missing son.