Williams picked up the problem during Wales 19 – 13 victory over Ireland at the Millennium Stadium on Saturday, but was able to finish the game.
However, after injury assessment on Sunday he was sent for a scan later that day which has since revealed ligament damage.
“Shane will be out of action for a period of six to eight weeks after sustaining damage to the posterior cruciate ligament in his left knee during the match at the weekend,” said Wales’ medical manager Prav Mathema.
“Thankfully there is no need for surgical intervention and he will now undergo a period of rehabilitation which will see him return to full fitness.”
Wales coach Warren Gatland has already added Scarlets wing George North to his squad in advance of the trip to Stade de France and there are no further call-ups expected.
The Wales side to face France will now be named on Thursday 17th March after Gatland took the decision to allow extra training time for players throughout his squad to make their bids for selection
