London: As many as 55 Chinese soldiers, including the captain and 21 officers, onboard Chinese nuclear-powered submarine 093-417 were killed after a catastrophic failure poisoned the crew on August 21, UK-based The Times has reported citing leaked British intelligence reports.

The incident took place in the Yellow Sea when the submarine was allegedly caught in a trap intended for American and British vessels.

The submarine reportedly ran out of oxygen near Shandong province, north of Shanghai, after becoming ensnared in seabed defences set up by its own forces.

However, both China and Taiwan have denied the loss of the submarine.

"Our understanding is death caused by hypoxia (lack of oxygen) due to a system fault on the submarine," it quoted British intelligence officials as saying in the report.

"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 on-board oxygen system poisoned the crew after a catastrophic failure," it added.

The classified intelligence is expected to prompt an investigation into the leak.

Speculation regarding the Shang-class submarine incident circulated on social media over a month ago, but the Chinese government refuted the claims.

China possesses six Type-093 attack submarines, each with a displacement of 6,096 tonnes and equipped with 553mm torpedoes.

These nuclear-powered submarines, engineered for reduced noise levels compared to earlier models, have been operational for the last 15 years, according to The Times' report.