The Russian navy has launched an operation to rescue seven crew members of a deep sea diving vessel that is stuck about 200 metres down in Pacific waters.As a big rescue operation, involving Russian and Japanese ships, got under way to bring the crew up, naval officials suddenly revised their earlier assertions that the crew had enough air to last them several days. “It has been established that there is only 22 hours supply of air on the AS-28,” chief naval spokesman Alexander Dygalo was quoted as saying on Friday by Interfax news agency. The “Priz” AS-28 mini-submarine, used in rescue operations, ran into trouble on Thursday during a military exercise south of the town of Petropavlosk-Kamchatskii, in the Kamchatka peninsula. Officials say experts are looking for a way of releasing the 13-metre-long vessel whose propellers reportedly got stuck in a fishing net. Alexander Kosolapov, spokesman for the Russian Pacific Fleet, says: “The situation is unusual, but it should not be over-dramatized. Special underwater equipment will reveal the nature of the problem. Then ways of solving this problem will be discussed, ways of raising the vessel to the surface.” One report says another submersible will be lowered to free the “Priz”. Similar vessels were used in the failed operation to rescue Russia’s nuclear submarine Kursk, which sank together with its 118-men crew in the Barents Sea in August 2000.