A rarely seen French secret report on Adolf Hitler is among thousands of documents on 1920s Germany that are about to emerge from obscurity as part of a major overhaul of the French National Archives.

The yellowed, hand-written note from 1924 features a photograph of Hitler in a suit and tie, sporting his trademark side-parting and moustache. It is part of a treasure trove that had been gathering dust in a Paris mansion for decades.

"He is not an idiot but rather a very cunning demagogue," says the note on Hitler by an anonymous agent.

The agent presents Hitler as "the German Mussolini" and notes that he runs paramilitary groups "of the fascist type", but does not raise any particular alarm about the man who would go on to lead Nazi Germany and launch World War II.

Part of a huge archive from the period when French troops occupied part of Germany after World War I, the Hitler report was stored separately from the rest of the papers in a metal cabinet where France keeps its most important documents.

Built in 1791 during the French Revolution, it contains 800 pieces including the diary of beheaded King Louis XVI, the last letter written by his doomed wife Queen Marie-Antoinette, Napoleon's will and France's successive constitutions.

Seen only by a very privileged few, the Hitler report has now been extracted from the cabinet and will soon be available for historians to study, along with tens of thousands of other papers dating back to the French occupation of Germany.

Those documents were transported to Paris in 1930 and have been stored ever since in the bowels of the National Archives, housed in a magnificent early 18th century residence in the heart of the historic Marais district.

'Racist'

The papers, which include everything from spy reports on politicians to details of German industrial techniques that the French hoped to appropriate, were not analysed or indexed.

As a result, they remained hidden in more than 6,000 boxes, an unmanageable mass of raw material, inaccessible to historians and slowly deteriorating as paper-clips rusted, dust accumulated and ink faded from sheets as fine as cigarette paper.

All that changed four years ago, when the Archives launched a conservation project to examine every single one of the papers and create a detailed index that will be posted online.

"On both sides of the Rhine, there was a very strong demand from historians to work on the inter-war period, and particularly the roots of the Second World War," Isabelle Neuschwander, director of the Archives, said.

She said the newly organised archive would be moved to a new state-of-the-art storage facility which is being built in a Paris suburb. There, the papers will be kept in much safer conditions and will be accessible to any researcher.

As well as Hitler, the French agents in Germany scrutinised other men who would go on to become powerful Nazis including Joseph Goebbels, Hermann Goering and Heinrich Himmler.

The Himmler note goes straight to the point: the first word is "racist".

Industrial espionage

Also under the French spotlight was Konrad Adenauer, the then mayor of Cologne who would become the architect of the West German state after World War II. But whoever wrote the Adenauer report did not take the full measure of the man.

"Competent but drawn to subordinate roles," the note says.

Michele Conchon, an archivist who has been working full-time on the German papers for the past four years, said that while the most eye-catching pieces were the reports on famous Nazis, they were not the most valuable to historians.

"That is not what interests me most. This archive is extremely rich in what it can teach us on daily life in Germany between the wars," she said, surrounded by boxes of dusty files.

She mentioned reports on violent incidents in which ordinary Germans showed their anger at the French occupation, burning French flags or attacking isolated soldiers guarding buildings.

The boxes also contain reports detailing German technological brilliance in areas as diverse as aviation, pharmaceuticals and wireless communications.

"There are reports of factory visits that were probably carried out with the aim of industrial espionage," she said.

The secret service reports even offer insights into the lives of ordinary Germans - and into the nervousness of the French, who kept close tabs on German public opinion.

Thus, a report on an obscure schoolteacher, named as Mr Hinze, reveals surprisingly close scrutiny.

"Schoolteacher, 31, neutral, no obvious prejudices, content with our occupation which ensures order, hopes to see us go when peace will be signed," says the report on Mr Hinze.

- Reuters