The Ministry of Defence has condemned the “desecration” of maritime military graves after reports scavengers had targeted two World War Two wrecks.
A vessel, thought to be Chinese, has been seen at the site the British ships were sunk, off the coast of Malaysia.
Some 842 British sailors died when HMS Prince of Wales and HMS Repulse were torpedoed by Japanese aircraft.
The attack on 10 December 1941 is seen as one of the worst disasters in British naval history.
It took place just three days after the attacks on the US fleet in Pearl Harbour, and two days after Japan invaded South East Asia.
The Prince of Wales was one of the Royal Navy’s most important battleships but it, and the battlecruiser HMS Repulse, had been sent to sea without any aircraft to protect them.
The ships are resting on the bed of the South China Sea, 60 miles (100km) off the east coast of Malaysia.
Source: BBC