A year ago, just before the NATO military intervention in Libya — in which France played a major role — Colonel Qaddafi’s son Saif al-Islam said that the government of Libya had helped to finance the campaign of Mr. Sarkozy. His aides denied the allegation at the time.        The document was leaked to Mediapart after it was referred to in evidence gathered in a judicial inquiry into another matter. That investigation focuses on whether kickbacks from the sale of submarines to Pakistan were used for political purposes 17 years ago to finance the presidential campaign of Édouard Balladur through the mysterious agency of an arms dealer named Ziad Takieddine. Mr. Takieddine, who liked to play middleman between various dictators and French politicians, is said by Mediapart to have helped arrange the 2005 meeting in Libya.