French investigative judges have summoned the former CEO of nuclear giant Areva for an all-day hearing over the company's disastrous investment in African uranium mines.

The national financial prosecutor's office said Friday that judges may decide to hand Anne Lauvergeon preliminary charges or give her the status of "assisted witness," the step before being a charged suspect.

Investigators are looking into whether Areva, then-chaired by Lauvergeon, deliberately submitted misleading annual accounts for the financial years 2010 and 2011. These accounts may have concealed huge write-downs due to the ruinous investment in Uramin, a Canadian company that was supposed to exploit African uranium deposits.

Areva bought Uramin for 1.8 billion euros in 2007 but, after Lauvergeon quit as CEO in 2011, the subsidiary lost 80 percent of its value.