"We are hoping that Martyn will be back with us before the end of the week, but he needs to be doing what is best for him at the moment," said Wales team manager Alan Philips.
"We want him to be away for as long as he needs and the thoughts of the squad and management team are very much with him at this difficult time."
Meanwhile, Llanelli Scarlets back row Dafydd Jones has been added to the Wales squad for the Invesco Perpetual Series Jones, who scored the winning try in the Scarlets' 15-13 victory over Edinburgh on Saturday was not included in Wales coach Mike Ruddock's initial squad due to injury.
However, after taking part in his side's Heineken Cup match on Saturday, he joined the rest of the squad this morning (Monday) as Wales prepare to play New Zealand on Saturday.
He takes the number of players in the squad to 32.
"It is great to have Dafydd back playing again and he showed his quality on Saturday in scoring the last-minute try for the Scarlets to win the game,"
"Dafydd makes a huge contribution to the Wales squad both on and off the field.
"As far as fitness is concerned, there is no issue with Dafydd as his recent injury was to his finger but it was important to see how he would come through Saturday's match and he performed superbly well."