Incorrectly stowed and secured cargo may have caused the shipwreck of Bulgarian vessel Vanessa, which sank in the Azov Sea on Thursday.

Sources close to the investigators of the tragic incident have said that the scrap metal cargo may have come out of place during the deadly storm and punctured the ship's shell.

Experts are also trying to find out if the 35-year old Vanessa was in a good technical condition.

The investigation on the case will last for at least three months, National Investigation Service official Georgi Iliev said on Tuesday.

Bulgarian investigators are working on six versions concerning the reasons for the ship's sinking, including that business interests lay behind it, as claimed by Ukraine's Transport and Communications Minister Yosip Vinsky.

He said the vessel refused help twice in the beginning of the storm last week, as the owner of the ship probably decided to save money on the rescue operation.

Mechanic Nikolay Dimitrov who is the only survivor so far of the 11 crewmembers aboard Vanessa, arrived Wednesday in the coastal city of Burgas.

Dimitrov who was rescued after spending 10 hours in the ice-cold waters said he will speak to the media about the tragedy on Thursday.

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