China's claim that the hull of the vessel contained no human remains, identity tags, watches, rings or other personal items has provoked anger among relatives of the men who died

On 9th June 1931 HMS Poseidon was exercising 20 miles north of her home base of Wei Hai Wei when the steamer Yuta was spotted some distance away. Despite excellent visibility, the two vessels collided and the submarine sank within two minutes.

The Poseidon was barely two years old and among the most modern submarines in the British fleet when it arrived at a leased British naval base on Liugong Island, four kilometers (2.5 miles) offshore from the port of Weihai. While conducting exercises on June 9, 1931, the captain inadvertently turned into a Chinese cargo ship that had altered course in the same direction to avoid hitting the submarine, which was travelling on the surface.

Its hull shattered, the Poseidon sank within four minutes, coming to rest on the sea floor 30 meters (100 feet) below. Thirty men scrambled out of hatches before it went down, but 26 remained inside, eight in the watertight forward torpedo room.

Salvage

It was a brief reference to the raising of the Poseidon during the Cultural Revolution that caught the attention of American maritime historian Steven Schwankert.

Subsequent inquiries led to evidence that the Chinese salvaged the vessel without informing London in order to test the skills of their naval special forces and newly formed underwater recovery units, as well as to clear a fishing area of a hazard that had been damaging fishermen's nets for four decades.

Chinese authorities informed UK's Ministry of Defence that "due to the long time that has passed and the lack of effective record keeping during that turbulent period of Chinese history, they have no more information than that which appears on the Shanghai Salvage Bureau's web site."

While it is accepted that little more can be done to protest the raising of the vessel, there are hopes that China might be encouraged to conduct a new investigation into the remains of the crew, which experts believe would have been recovered