"Because of the fact the injury had not made any significant progress further investigations where carried out by our medical staff, which have revealed damage to the ligament that surrounds the bone between the first and second metatarsal," said Ruddock.
The Coach has called Ospreys flanker Richie Pugh into the Wales camp to cover for the injury which his vice-captain picked up playing for Newcastle in the Heineken Cup. The doubt over fellow flanker Williams, who has a disc problem in his neck, has also led the Wales coach to call Cardiff's Robin Sowden-Taylor to train with the squad.
"Due to the injuries we have in the back row Richie will officially join up with the squad and Robin will train with us as an attached player," said Ruddock. "Richie has been outstanding for the Ospreys and Wales U21. He gained National Squad experience on the summer tour of Argentina and South Africa."
Colin Charvis said: "This is obviously a huge disappointment, but all I can do is continue with the programme of rest and treatment the Wales team doctors have prescribed for me.
"The injury has not responded as quickly as I had hoped and the prognosis is that I could be out for another two to three weeks. I'll just get my head down now and hopefully see the rest of the guys do well until I can return."