Thirty-nine living relatives of Adolf Hitler have been discovered by a customs official and a journalist who claim to have decoded the Nazi dictator's DNA.

Analysing forgotten cigarette butts in a small village in lower Austria, a used paper serviette in a New York fast food restaurant and the seals of letters sent over 30 years ago from northern France, Marc Vermeeren and Jean-Paul Mulders said they had traced all known living relatives of the Fuehrer for the first time.

As well as three living in America, whose existence has been reported previously, they claim to have tracked down 36 others who still live in the wooded area of Austria where Hitler was born.

Mr Vermeeren, a Belgian customs official, and Mulders, a journalist for Belgian newspaper Het Laaste Nieuws, said three great-grandchildren of Hitler's father, Alois, lived on Long Island, outside New York, under the false name Stuart-Houston. They are descendants who left Germany to escape the Nazis.

Louis and Brian Stuart-Houston share a little wooden house in East Patchogue, where they work as gardeners, while Alexander is a retired psychologist who helps Vietnam veterans.

The Belgians said they had watched them for seven days and nights, following 60-year-old Alexander to a fast-food restaurant where he disposed of a paper serviette after eating fried chicken that they retrieved and later matched with ''DNA of Hitler that we keep in a sealed, armoured chest'', according to Mulders.

The cigarette butts came from Hitler relatives in Austria, they said.

''The American relatives have agreed not to have children to extinguish the saga of Hitler and stop living in fear, but have promised to publish a book before they die,'' said Mulders.