The Russian tanker Nakhodka, which broke apart and sank off the Sea of Japan coast in January, was too old and worn out to weather the rough seas, a Transport Ministry panel concluded July 31.

The panel's report brushed aside Russia's argument that the 13,157-ton tanker, which spilled at least 5,000 kiloliters of heavy oil and caused massive environmental damage on a wide coastal stretch, sank after hitting a submerged object. The ministry panel, led by Hideomi Otsubo, professor of engineering at Tokyo University, briefed Transport Minister Makoto Koga on the final result of its six-month investigation on the accident, which occurred off Shimane Prefecture on Jan. 2.

"Normally, ships are designed to last for about 20 years, whereas the Nakhodka was 26 years old," Otsubo told a news conference. "The accident was caused by the shipowner's policy (of continuing to use the aged tanker)." The 177-meter tanker broke apart 51 meters behind the bow, and it appears the ship was destroyed by a high wave almost instantly, according to the report.