Former French President Nicolas Sarkozy has been taken into custody for questioning, according to legal sources.
He is being investigated over alleged influence peddling, according to the BBC.
Hours earlier, it was reported that his lawyer and two magistrates had also been and interrogated as part of a corruption probe involving Sarkozy.
Investigators are trying to find out whether lawyer Thierry Herzog helped Sarkozy to pervert the courts of justice and sought to provide him inside information on another probe.
Sarkozy allegedly promised a magistrate to have a prestigious role in Monaco.
Influence peddling could carry a maximum sentence of 10 years under French law.
Sarkozy, who lost 2012's presidential vote to socialist rival Francois Hollande and left the Elysee Palace, has repeatedly stated his intentions to run again in 2017.
He is facing a number of probes, with investigators also looking into alleged financing of his 2007 presidential campaign from former Libyan leader Muammar Gaddafi.
The former President was previously cleared of charges that he had also received money from France's richest woman Liliane Bettencourt to run that campaign.
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