12 dead bodies have been found on the place where a Ukrainian helicopter Mi-8 crashed in the Black Sea today.

According to Ukraine`s Border Troops press-service chief Serhiy Astakhov, there was one survivor from the mishap taking place in the north- western Black Sea, near the mouth of the Danube River.

A total 13 persons, 3 flight crew and 10 passengers, had been aboard the aircraft at the time of the crash.

The Ukrainian border troops Mi-8 helicopter had been carrying personnel and supplies to Zmeyniy Island, a rocky outcrop claimed by some 60 kilometres south of the Danube`s mouth.

The single survivor was in "serious condition," said Serhiy Astakhov, a border troops spokesman.

According to DPA, the flight from the mainland to Zmeyniy Island by Mi-8 lasts approximately 45 minutes. It was not clear when exactly, or for what reason, the helicopter had crashed.

The downed helicopter was visible in shallow water, and had apparently almost reached the island before hitting the water, witnesses said.

Two motor launches were combing the area, and a pair of helicopters was en route to assist in the search for other survivors.

Ukraine has seen unsettled weather in recent days, with snows even in lowlands and temperatures hovering slightly above freezing, alternating with sunny weather from 10 - 13 degrees Centigrade.

Zmeyniy Island is the site of a Border Troops station maintained by Ukraine on the 1.5 square kilometre rock to buttress a Kiev claim to territorial waters in the region.

Neighbouring Romania says the claim is baseless and the border troops installation meaningless, as Zemyniy Island has always been uninhabited.