The rumour was that Marseille ACC were going to strike every weekend, and looking at the info they have announced a strike today from 0430UTC this morning until Monday 28th at 0430UTC, so 48 hour walkouts. They are still providing a service, just not enough staff to meet demand so are having to regulate portions of airspace. The railways in France are striking for 48 hour periods every week for the entire month too and it isn't uncommon for the rest of the public sector workers to just decide to go out in support too, sometimes with less than 48 hours notice. The best place to find out accurate information is at the
Eurocontrol NOP website.