The 28-year-old has delayed linking up with Giovanni Trapattoni's squad for the coming week's games against Andorra and Armenia to undergo a scan on an ankle injury.
Walters had been poised to resume his international career after recently being left out by Trapattoni.
Ireland play in Andorra on Friday and then host Armenia next Tuesday knowing that two victories will at least seal a play-off spot.
A slip-up by Russia could even give the Irish the chance to finish top of their group.
Source: Team Talk
Source: Team Talk