The national council of the Socialist Party has checked last week's vote and discovered that the margin of votes cast for Ms Aubry had actually increased from 42 votes to 102.
However, due to past infighting followed by this protest by Ms Royal the French media has suggested that the Socialists look set to split into two camps.
58-year-old Ms Aubry, who is also the mayor of Lille and past-employment minister, is the first woman leader of the French Socialist Party, and she is taking over from Francois Hollande, who is Ms Royal's former partner.
