Carcela, 21, was born in Belgium to a Moroccan mother and Spanish father, has played for Belgium's under-21s and also come on for the senior side in friendlies in the past year.
However, despite being called up for the Euro 2012 qualifiers against Germany and Turkey, Carcela did not show up, releasing instead a short statement on his club's website.
"Mehdi Carcela has not made his mind up. As long as that remains the case, he does not wish to line up for an official match of the A-teams of Belgium or Morocco," the statement said.
He said he would be willing to play for Belgium's under-21s in their match in Slovenia on Friday although the Belgian football federation decided not to use him.
The rules of world football governing body FIFA stipulate that players with more than one nationality may switch countries assuming they have not played in an official competition for a senior national side.
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