Experts say the damage from the Black sea disaster may reappear each spring. Several sailors are dead and emergency teams are still battling to clean the massive oil spill in the Kerch Strait. In all, five ships sunk during the region's worst storm in 30

The search for who's responsible has begun, as ship captains and port officials point the finger at each other.

Vladimir Slivyak, from the international Ecodefence group, believes the invisible consequences will continue damaging the region for years.

“About 30% of the oil goes down to the bottom of the sea. So each spring, as the water gets warmer, the oil will come out, causing a new contamination,” Slivyak said.

Ukraine's President Viktor Yuschenko is proposing a new agreement with Russia on the joint use of the Kerch Strait. Speaking in Israel, the President said new transport regulations for the area would help prevent future environmental disasters.

The body of one more sailor has been found in the Kerch Strait. All in all more than five have died, and 19 others are still missing.

A massive oil slick remains where the Volganeft-139 tanker broke in half, spilling about 2,000 tonnes of oil into the water, and several other ships, carrying hazardous chemicals, sank during the region's worst storms for 30 years. The overall number of vessels damaged reached 15 on Thursday.

The damage from Sunday's storm in the Kerch Strait in Russia's southern region is expected to exceed over $US 12 billion.

Oil moving towards Azov

Thousands of birds were trapped in the oil spill for more than three days, freezing in the cold rain. Some were saved by local hunters.

Hundreds of kilometres of the Azov Sea coast are also covered in thick oil, meaning local fishermen are out of work. The Taman fish cannery has stopped shipments, and starting Sunday all fishing in the area has been prohibited.

Sea water tests show the level of oil is 50 times above the maximum permitted levels.

Cleaning work at the sea coast

Igor Chestin from the World Wildlife Fund says the clean-up operation will be more difficult, if the oil sinks to the seabed.

“Unfortunately, these are the heavy fractions of oil – mazut – which is heavier than water, so it actually sinks. Because of the storm, most oil is still staying on the water surface. But when the storm will go down it will settle on the bottom in probably quite a large area,” he explained.

More than 3000 tonnes of oil along the coastlines of Russia and Ukraine has already been collected.

An oil slick is moving towards the Azov sea, and authorities are hoping to stop it from spreading by putting up a boom across the Kerch Strait. Some anti-pollution bars have been placed there already.