The Africans were kicked out of the final stages of the CAF qualifying competition for Brazil 2014 after being punished for fielding an ineligible player in the win over Tunisia in September.
They had topped Group B of African qualifying after their 2-0 win over Nabil Maaloul's men in Rades. However, FIFA found the Cape Verdean Football Association guilty of fielding Fernando Varela, despite the defender not having served a full four-match suspension for a red card.
As a result, Tunisia were awarded a 3-0 walkover - enough to move them top ahead of Cape Verde and into a two-legged play-off clash with Cameroon instead of their opponents.
Cape Verde appealed the original ruling, but their case was dismissed early in October - prompting the nation's FA to now take the issue up with the CAS.
A statement from CAS read: "The Court of Arbitration for Sport (CAS) has dismissed the appeal filed by the Cape Verdean Football Federation (FCF) against the FIFA Appeal Committee (the FIFA AC) decision of 23 September 2013.
"In such decision, the FIFA AC entirely confirmed an earlier decision of the FIFA Disciplinary Committee (FIFA DC) in which the FCF was found to have fielded an ineligible player during a FIFA World Cup qualifying match against Tunisia and sanctioned with the loss of the match 3-0.
"Consequently, the results of the qualifying rounds for the FIFA World Cup 2014 remain unchanged."
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