Experts believe a 22ft German torpedo discovered in the Scapa Flow may one of three unaccounted for bombs from one of Britain's most infamous naval disasters.

It is believed the torpedo may be one of three which missed the HMS Royal Oak before four direct hits.

The discovery is one of the final pieces in the jigsaw of what happened when the British warship sank on October 14, 1939.

The bombing destroyed the former flagship Navy boat with the loss of 833 lives during the Second World War.

It did not have a huge impact on the war effort as the Royal Oak had been pulled back from frontline service due to its slow speed but it was said to have had a huge impact on the morale of the country.

The wreck of the HMS Royal Oak now lies on the seabed in the Scapa Flow and is a protected war grave.

Earlier this week, Orkney Islands Council confirmed an unidentified object was discovered during a sonar survey of the water near the site of the sunken ship.

Royal Navy divers then investigated the site and confirmed the object was a G7e torpedo.

Ships have been warned not to drop anchor in the area and 1640ft exclusion zone has been established around the torpedo, which is lying more than 100ft under water on the seabed.

A spokesman for Orkney Islands Council said a remote-operated vehicle (ROV) was used to investigate the object further after its initial discovery. A Royal Navy Explosives Ordnance Team then looked at the footage and sent in Royal Navy divers.

Brian Archibald, the council’s harbour master and head of marine services, said: "This has confirmed that it is a torpedo and that it is German in origin.

"We have held further discussions on what action should be taken next, with plans now to be drawn up for its safe disposal. Meanwhile, there is no risk to vessels in Scapa Flow."

The wrecks of two experimental anti-torpedo vessels used during the Second World War were recently discovered in the Scapa Flow, one of the world's biggest ship graveyards.

The popular diving destination was home to the British Grand Fleet during the First and Second World Wars.

The Scapa Flow came under attack in the first months of the Second World War and the HMS Royal Oak was sunk by a German U-boat in in October 1939.

Kevin Heath, of Sula Diving, which discovered the torpedo, said he is "very confident" the torpedo is from the historic incident.

He said: "This is a very exciting discovery. It's definitely the torpedo from the Royal Oak incident. No other U-boats were operating in Scapa Flow during the Second World War.

"There were three torpedos that missed out of seven shots in total. Four of them hit and caused the ship to sink.

"The U-boat commander Günther Prien actually wrote in his logbook that three torpedos had 'gone to the devil'.

"Where we found this one is exactly where the U-boat was when it fired at the Royal Oak. We knew very quickly that it was likely to be this torpedo because it's longer than any British torpedo. When we went out in the ROV, that confirmed it.

"I think it's come of the torpedo tube but then the motor has failed and it sank to the seabed."