A cargo ship with 700 tons of gold ore on board missing off the coast of Russia's Far East did not have permission to sail, RIA Novosti news agency reported Thursday.

An investigation found the freighter, Amurskaya, with nine crew members aboard, left the port of Kiran without receiving permission from authorities, and was in breach of the minimum crew requirement, the report said. < The investigation also showed the vessel was not equipped for the transportation of bulk cargo, and was not certified fit to transport raw materials, it said.

Investigators beleived the cargo on board weighed 700-750 tons, well beyond its capacity of 611 tons, according to the report.

A criminal case has been opened to investigate the vessel's disappearance.

No traces of the freighter have been found and investigators believe it might have sunk due to a storm in the area at the time, technical failure and violation of navigation rules.

Amurskaya disappeared en route to Okhotsk on Sunday after sending out a distress signal in the Okhotsk Sea.