This is according to a secret report coming out of the United Kingdom, which alleges that the Chinese Navy sailors died in August from poisoning due to a catastrophic failure in the nuclear submarine's oxygen systems. (Related: Reports: Advanced Chinese nuclear submarine crashed in Taiwan Strait.)
The incident is said to have occurred on Aug. 21 in the Yellow Sea waters off China's northeastern Shandong Province, just miles across from North and South Korea.
The classified British intelligence briefing alleges that a submarine called 093-417 struck a chain and anchor obstacle set up by the Chinese, which is meant to trap Western submarines.
The collision led to system failures and a six-hour struggle for the 093-417 to surface. It also led to the submarine's onboard oxygen systems failing catastrophically, poisoning the crew. Fifty-five sailors died, including the captain – Col. Xue Yong-Peng.
Chinese rescuers dove and were reportedly able to rescue just one survivor.
It isn't entirely clear how the 093-417 collided with the trap in the Yellow Sea nor how the trap mangled the submarine's oxygen systems. It also isn't entirely clear whether the crew began suffocating in the submarine before it began sinking.
The submarine 093-417 is one of China's Type 093 "Shang-class" nuclear-powered submarines, one of the PLAN's most modern subs. It was first built nearly 30 years ago and entered active service with the PLAN in 2006. At least six of the 351-foot-long submarines are active in the Chinese Navy.
It can travel up to 30 knots (35 miles) when fully submerged and is known for its stealth capabilities, emitting significantly lower noise levels compared to submarines of a similar type. The Type 093 can be outfitted with torpedoes and anti-ship cruise missiles.
The British intelligence report was classified as very high level and was shared by an intelligence staffer on condition of anonymity with U.K.-based media outlet the Daily Mail. The full report remains undisclosed.
When questioned by the Daily Mail, spokespersons in Beijing denied that such an incident took place, dismissing the speculation as "completely false." Intelligence agencies in neighboring Taiwan have also raised skepticism about the report. The British Royal Navy has also declined to comment on the Daily Mail's report.
However, one Royal Navy submariner who spoke with the Daily Mail suggested that it is plausible that the accident took place and is being actively covered up by the Chinese.
"It is plausible that this occurred and I doubt the Chinese would have asked for international support for obvious reasons," said the submariner in an email. "If they were trapped on the net system and the submarine's batteries were running flat (plausible) then eventually the air purifiers and air treatment systems could have failed."
The submarine at this point would have then reverted to its secondary life support systems, which could also plausibly fail to maintain the air in the enclosed space, leading to asphyxia or poisoning for the crew.
"We have a kit which absorbs [carbon dioxide] and generates oxygen in such a situation," wrote the source. "It is probably that other nations do not have this kind of tech."
Learn more about recent events concerning China at CommunistChina.news.
Watch this episode of "Evolutionary Energy Arts" as hosts Michael and Cindy Lazaro discuss the alleged crash of a Chinese nuclear submarine in the Taiwan Strait in August.