In reply to hatman:
According to this
http://www.ffme.fr/site/falaise-fiche/126.html it is only allowed to climb in the following sectors: in Beauregard, from Mur Notre Dame to Grottes, and in the canal area from Fièvre to Initiation, ie page 204, sectors 1, 2, 3, 4, 5, 6, 7 and page 176, sectors 18, 19, 20, 21, 22, 23. All sectors in the valley are closed. There are also restrictions between June 1st and September 30th depending on the conditions and fire risks.