Former French prime minister Edouard Balladur has been charged over allegations that kickbacks from the sale of submarines to Pakistan may have helped finance his 1995 presidential election campaign, according to judicial sources.

For years, judges have been trying to unravel the "Karachi Affair", a series of nebulous dealings by middlemen involving possible "retro-commissions" linked to the sale of Agosta class submarines by the French government to Pakistan in the 1990s.

The investigation was launched after 15 people, including 11 French submarine engineers, were murdered in a May 2002 bomb attack in Karachi.