"The discovery of this plan is fundamental. This document establishes Petain's decisive role in drawing up this position in the most aggressive way, revealing (Petain's) deep anti-Semitism," Serge Klarsfeld told AFP.
Petain, a military hero in World War I, became head of the rump state based at Vichy in central France which collaborated with the German Nazi occupiers following defeat in World War II.
The penciled-in changes to the document, from October 1940, are a "profound alteration" of the document's nature, Klarsfeld said.
While the original set out to exclude "descendants of Jews born French or naturalized before 1860", Petain crossed out this reference, thus applying the measures to all Jews in France.
The scope of Jews' exclusion is considerably widened, with the minority being barred from jobs in teaching and the judiciary as well as prevented from standing for elected office.
"The main argument of Petain's defenders was to say that he protected French Jews. This argument has now fallen," he said.
The document came to light after an anonymous donor handed it in to the Holocaust Memorial in Paris, Klarsfeld said.
Klarsfeld and his son Arno, also a lawyer, compared the script to known examples of the wartime leader's handwriting and there is "no doubt" that the annotations are his, he said.
After Germany's defeat Petain was tried by the provisional French government of General Charles de Gaulle, who commuted his death sentence to life imprisonment, and he died in 1951.
There was previously only one testimony concerning Petain's anti-Semitism, from Vichy foreign minister Paul Baudouin.
'Desire to turn Jews into scapegoats'
In a 1946 book, Baudouin wrote that during the October 1, 1940 cabinet meeting, the government spent two hours examining "the status of the Israelites. It was the marshal (Petain) who was the most severe. He insisted notably that there should be no Jews in the judiciary or education."
"Baudouin's testimony was very clear but doubt could be cast on it. Now, we have definite proof that the Jews' status was the personal will of marshal Petain," said Klarsfeld.
Petain wanted "to show that France deserved to be at the forefront of the new European order. There was also the desire to turn the Jews into scapegoats for the defeat" of France by the Nazis, said Klarsfeld.
"The status of Jews was a specifically French measure, spontaneous. The Germans didn't ask Vichy France to take this measure. But there was competition between French and German anti-Semitism.
Nevertheless, of all Nazi-occupied countries, France was the one where "the Jewish community suffered the least tragic harm," said Klarsfeld.
Around three-quarters of the Jewish population survived, or around 240,000 out of 320,000.
"That's not thanks to France but to the French, thanks to all the courageous people who helped the Jews all over the place," he said.
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