Charlton had agreed a one-year loan deal with Costa Rican club Deportivo Saprissa for the 22-year-old earlier this month, subject to international clearance.

Bolanos has represented his country 18 times _ including in two World Cups _ but he did not meet the required quota of international appearances set by British immigration officials.

``We felt we had a very strong case,'' Charlton manager Iain Dowie said. ``Christian is an emerging talent and has become a fixture in the Costa Rica side despite his age, so it is very disappointing. Not just for us but for the lad as well.

``It causes us a problem because he fits the description of what we are trying to do at the club: he is athletic and very good technically. From my point of view, it is frustrating _ but more disappointing for the lad because he is a great kid.''