PARIS—French police raided the home and offices of former president Nicolas Sarkozy early Tuesday as part of a campaign-financing probe involving Liliane Bettencourt, heiress to the L'Oréal cosmetics empire, people familiar with the matter said.

About a dozen police searched offices Mr. Sarkozy has used since leaving the Elysée palace in mid-May, and the Paris apartment of his wife, Carla Bruni-Sarkozy, these people said.

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