The strike action is centred on a maintenance depot where there is a dispute over changes to working conditions.
It will affect the high-speed TGV routes running from Paris' Montparnasse station to Bordeaux, Rennes and Nantes and is expected to continue until Sunday.
The French rail operator estimates that 6 out of 10 services will be running, but there are likely to be delays.
En raison d'une grève locale, la circulation des TGV de l'axe atlantique (Paris Rennes/Nantes/Bordeaux) est perturbée : six trains sur dix circuleront sur cet axe jusqu'à dimanche inclus, indique la SNCF https://t.co/QUcbewgVeG pic.twitter.com/5sUteFXsph
— Le Parisien (@le_Parisien) October 24, 2019
Anyone whose pre-booked train has been cancelled should have already been notified by text message or email, but users are advised the check the SNCF app before they travel for more up to date information.
Cancellations of pre-booked tickets can be done for free on the SNCF website.
The strike has been declared by the SUD rail union and is centred on the Châtillon repair depot, which is responsible for the maintenance of the TGV and Ouigo trains.