Two executives at IKEA France are being questioned by police as part of a probe into allegations the company illegally used police files to spy on staff and customers, a judicial source said.

Stefan Vanoverbeke, IKEA France’s CEO, and CFO Dariusz Rychert were formally detained for questioning by police in Versailles on Monday, the source said.

The questioning was expected to last until late Monday, the source said.

The company’s former CEO, Jean-Louis Baillot, was also being questioned, a police source said separately.

IKEA representatives confirmed the questioning was taking place but refused to comment further.

French prosecutors launched a criminal probe in April 2012 following allegations that IKEA paid for illegal access to secret police files to gain information about employees and clients.

Keen to repair its reputation, IKEA France subsequently fired four employees, launched an internal inquiry and established a code of conduct to avoid a repeat of the scandal.

The questioning follows police seizures at the company’s headquarters in the Paris suburbs earlier this month.

Several people have been charged in connection with the case, including IKEA France’s former risk management head Jean-Francois Paris.

Four civilian police employees have also been charged and are suspected of having been paid by IKEA in exchange for confidential police files.

Media reports have said sources were paid about 80 euros ($A117.60) in each case to hand over files from the police file system, which tracks millions of names and personal information about criminals, victims and even witnesses.

Reports alleged IKEA France requested information on its own employees, including union members, the owners of certain car registrations and names associated with a list of mobile phone numbers.

In one case the company allegedly asked for personal information on a customer who was suing it.