The sinking of the first of a new Zhou-class of nuclear-powered submarines triggered a scramble for Beijing to cover up the incident, officials told The Wall Street Journal.
The newly built vessel, which features a distinctive X-shaped stern, was sighted on satellite images alongside a pier at Wuchang Shipyard as it was being equipped for sea in late May.
It is claimed to have sunk later that month or in early June. Suspicion was said to have been raised when floating cranes were seen at the site soon afterwards.