Sarkozy's lawyers said he would appeal the decision to send him to court, initially reported by the daily Le Monde.
The case came about after investigators used phone-taps to examine separate allegations that late Libyan leader Muammar Gaddafi funded Sarkozy's campaign and began to suspect he had kept tabs on a separate case through a network of informants.
The development came just over a week after Sarkozy was told he was being formally treated as a suspect in the election campaign investigation.
Sarkozy was president from 2007 to 2012 but was defeated by Socialist Francois Hollande when he ran for re-election. He has since faced a series of investigations into alleged corruption, fraud, favoritism and campaign-funding irregularities.
Sarkozy's lawyers had previously argued that magistrates investigating the alleged secret Libyan funding exceeded their powers and went on a "fishing expedition" by tapping his conversations with them between September 2013 and March 2014, breaching lawyer-client privilege.
Based on the intercepts, Sarkozy is accused of having discussed offering a promotion to a prosecutor in return for tip-offs on an investigation into accusations that his former party treasurer and others exploited the mental frailty of France's richest woman, Liliane Bettencourt, to extract political donations in cash.