A rare World War Two German bomber, shot down over the English Channel in 1940 and hidden for years by shifting sands at the bottom of the sea, is so well preserved a British museum wants to raise it.

The Dornier 17 -- thought to be world's last known example -- was hit as it took part in the Battle of Britain.

It ditched in the sea just off the Kent coast, southeast England, in an area known as the Goodwin Sands.

The plane came to rest upside-down in 50 feet of water and has become partially visible from time to time as the sands retreated before being buried again.

Now a high-tech sonar survey undertaken by the Port of London Authority (PLA) has revealed the aircraft to be in a startling state of preservation.

Ian Thirsk, from the RAF Museum at Hendon in London, told the BBC he was "incredulous" when he first heard of its existence and potential preservation.

"This aircraft is a unique aeroplane and it's linked to an iconic event in British history, so its importance cannot be over-emphasized, nationally and internationally," he said.

"It's one of the most significant aeronautical finds of the century."

Known as "the flying pencil," the Dornier 17 was designed as a passenger plane in 1934 and was later converted for military use as a fast bomber, difficult to hit and theoretically able to outpace enemy fighter aircraft.