The wreckage of a prototype submarine containing one of the world's first periscopes is to get protection from trophy hunters.

Launched in May 1902, the Holland 5 was the last of five vessels built for the Admiralty to test the submarine's potential as a weapon.

While on tow from Portsmouth to a shipbreakers yard in Sheerness, on August 8, 1912, the 120 tonne craft sunk in 31m of water off Beachy Head.

Heritage minister Andrew McIntosh has announced the site of the wreck, discovered five years ago, will be designated under the Protection of Wrecks Act.

The order, which came into effect yesterday, will make it illegal for divers to tamper with the site without authority.

It has been made due to the historical importance of the vessel. This includes its periscope which was invented by the submarine service's first captain, Roger Bacon.

Using a ball-and-socket joint to raise and lower itself, this type of periscope remained virtually identical throughout the First World War.

Mr McIntosh said: "The Holland 5 played a short but significant role in the evolution of the British submarine and the survival of this boat gives a unique opportunity to study the technology of the time, including the possible prototype of the submarine periscope.

"Only two of the Holland submarines survive today.

"The Holland 5 is thought to be intact and in good condition.

"I am pleased this order will preserve the wreck site allowing proper study of the vessel and preventing any vandalism by trophy hunters."

Built by Vickers & Maxim, the Holland 5 served with the First Flotilla at Fort Blockhouse until its removal from the navy in August 1912.

The Hollands were invented by Irish Fenian John Holland who had emigrated to the United States.

They were the first submarines commissioned by the Royal Navy and were all built in a short period between October 1901 and May 1902.

Manned by a crew of seven, each of the craft was driven by a four cylinder petrol engine while on the surface and an electric motor while submerged.

All five boats had been disposed of by October 1913 after being rendered technically obsolete.

Apart from Holland 5, the first Holland submarine is the only other to survive and was salvaged from the sea bed in 1982.

It is now on display at the Royal Naval Submarine Museum at Gosport, Hampshire.