Twelve people are feared drowned after their boat capsized in the Black Sea near the Ukrainian city of Odessa.

Officials said the boat had been carrying 36 people at the time of the sinking. Twenty-three were rescued.

It was not immediately clear what caused the incident, close to Zatoka town. One report said it was a passenger boat, another said those on board were mostly fishermen.

The Kiev government has launched an investigation.

The regional governor, ex-president of Georgia and now Ukrainian citizen Mikheil Saakashvili, cut short a visit to western Ukraine to attend the scene of the incident.