PARIS—French magistrates have pressed preliminary charges against Bob Dylan, a poster child of the American civil-rights movement, for allegedly violating antidiscrimination laws in a 2012 magazine interview in which he appears to compare Croatians to Nazis and the Ku Klux Klan.

The probe is a turn of fortune for the iconic American singer in France, where just three weeks ago he was awarded the country's highest cultural award, the Légion d'honneur.

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