Lock Jones was forced off the field during the defeat to France at the Millennium Stadium last Friday night with a rib injury and will now join his Regional colleague Williams, who has been unavailable since picking up a knee problem against Scotland over a fortnight ago, in the treatment room at the Blues.
Warren Gatland and his fellow Wales coaches have made no moves to replace the injured pair at this stage and will also release a further 14 players back to their respective Regions after national squad training this Wednesday (3rd March), making them available for selection for Magners League matches at the weekend.
Scarlets hookers Matthew Rees and Ken Owens will both be in the selection mix to face Ulster at Parc y Scarlets on Friday night (K.O. 19.05hrs) as will centre Jonathan Davies.
Lock Luke Charteris and flanker Dan Lydiate will return to Dragons duty in time for their meeting with Munster at Rodney Parade on Saturday (K.O. 18.30hrs).
For the Ospreys, Mike Phillips, Andrew Bishop, Dan Biggar, Tom Prydie and Kristian Phillips will all be available for back line duty and Ian Gough will be ready to return to the forward pack which takes on Edinburgh in Murrayfield on Sunday (K.O. 14.00hrs).
Finally, flanker Sam Warburton and backs Tom Shanklin and Tom James will be available for the Blues as they host Leinster at the Cardiff City Stadium late on Sunday afternoon (K.O. 1600hrs).
