Washington: China tried to hide the sinking of its most sophisticated nuclear-powered submarine earlier this year, a senior U.S. defense official said last night.

While Chinese-language news sites reported about a submarine sinking at a shipyard in China (an event first broken by The Wall Street Journal), satellite images soon appeared showing the trapezoidal shadows of large, bright cranes moving toward the water to lift the damaged vessel.

"Given that this is the first boat of a new class, it's hardly surprising that the PLAN would try to suppress whatever happened," said a U.S. official, using the abbreviation for People's Liberation Army Navy. The official also complained about training standards, equipment quality and broader issues of corruption and oversight within China's defense industry.

The breakout is considered a major blow to China's naval modernization. While it is the largest navy in the world, with more heavy and medium surface warships than any country, much of what China calls a navy are smaller scale warships like frigates and corvettes.

Asked about the reports, China's foreign ministry said it had "no information" on the matter.

Regardless, the US (US) and UK are proceeding with plans to deliver nuclear-propelled submarines to Australia as part of a counterpunch against China's heightened Pacific military presence. Beijing has objected to this trilateral endeavor, which also envisages building joint warfighting capabilities.