Galtier was appointed midway through last season to succeed the sacked Marcelo Bielsa and the Frenchman's success reviving their fortunes since has meant Lille were determined to extend a deal that was set to expire at the end of this campaign.

The 52-year-old Galtier, who played for Lille in the late 1980s, previously enjoyed a successful eight-year spell in charge of Saint-Etienne.

After narrowly avoiding relegation last season, Lille are currently second in Ligue 1 and in contention for a return to the Champions League -- they last appeared in the group stage in 2012-13.