UK intelligence says 55 sailors from China's nuclear-powered submarine dead

Fifty-five Chinese sailors are feared dead after their nuclear submarine apparently got caught in a trap intended to ensnare British sub-surface vessels in the Yellow Sea.

According to a secret UK report the seamen died following a catastrophic failure of the submarine's oxygen systems which poisoned the crew, Daily Mail reports.

The captain of the Chinese PLA Navy submarine "093-417" is understood to be among the deceased, as were 21 other officers.

Officially, China has denied the incident took place. It also appears Beijing refused to request international assistance for its stricken submarine.

The UK report into the fatal mission reads: 'Intelligence reports that on 21st of August, there was an onboard accident whilst carrying out a mission in the Yellow Sea.

"Incident happened at 08.12 local resulting in the death of 55 crew members: 22 officers, 7 officer cadets, 9 petty officers, 17 sailors. Dead include the captain Colonel Xue Yong-Peng.

"Our understanding is death caused by hypoxia due to a system fault on the submarine. The submarine hit a chain and anchor obstacle used by the Chinese Navy to trap US and allied submarines.

"This resulted in systems failures that took six hours to repair and surface the vessel. The onboard oxygen system poisoned the crew after a catastrophic failure."

As yet there is no independent confirmation of the suspected loss of the Chinese submarine in the public domain. 

Beijing has dismissed open source speculation about the incident as 'completely false' while Taiwan has also denied internet reports.

Mail Plus approached the Royal Navy to discuss the details contained in the UK report but official sources declined to comment or offer guidance.

The UK report, which is based on defence intelligence, is held at a high classification.

A British submariner offered this explanation: "It is plausible that this occurred and I doubt the Chinese would have asked for international support for obvious reasons.

"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.

"Which would have reverted to secondary systems and subsequently and plausibly failed to maintain the air. Which led to asphyxia or poisoning.

"We have kit which absorbs CO2 and generates oxygen in such a situation. It is probable that other nations do not have this kind of tech."

The Chinese Type 093 submarines entered service in the last 15 years. The vessels are 351 feet long and are armed with torpedoes.

The Type 093s are among China's more modern submarines and are known for their lower noise levels.

The sinking is understood to have taken place in waters off China's Shandong Province.