Northern Ireland boss Nigel Worthington has revealed his frustration at seeing Everton defender Shane Duffy opt to play for the Republic.The 19-year-old played for Northern Ireland at every youth level and was included in Worthington's squad for the 3 March friendly against Albania. [LNB]"It is a disappointment for me and all the Northern Ireland coaches who have worked with him," said Worthington. [LNB]"I think it is a ludicrous situation which needs to be resolved." [LNB][LNB] [LNB][LNB] Duffy, who was on the bench for Northern Ireland's friendly against Pisa last June, was in the squad list for Albania circulated to journalists on Monday morning. [LNB]He looked set to win his first cap in the absence of captain Aaron Hughes and his defensive team-mate Chris Baird. [LNB]However, Duffy, who has made two appearances for Everton in the Europa League this season, sees his future with the Republic. [LNB]He had come through the system with Northern Ireland, captaining the Under-19s before graduating to the Under-21s. [LNB]"I had spoken to him on a couple of occasions and had swung him back to ourselves, but he had further thoughts," revealed Worthington. [LNB][LNB] If Shane Duffy wants to play for the Republic then the best of luck to him Returnoffatladni "He was sorry because he had been treated very well by Northern Ireland - but he had made his decision. [LNB]"It is frustrating from the Irish Football Association's point of view. [LNB]"Until it is changed, I can see Northern Ireland producing players who then nip off to join another country. [LNB]"There is a loophole where a player can walk away after a lot of time and investment has gone in. Until it resolved, that is where we are. [LNB]"Shane has represented Northern Ireland all the way through from a very early age to the Under-21s. [LNB]"I am a big admirer of Shane. I like him as a player and a lot of work has gone in with different coaches. I am disappointed with the situation as he is going to be a very good player." [LNB]Duffy's case is similar to that of Manchester United midfielder Darron Gibson, who played at underage level for Northern Ireland but is now an established senior player for the Republic. [LNB]Even if Duffy had come off the bench against Italy last summer, he could still have opted to switch to the Republic. [LNB]The move could only have been blocked if he had played in a competitive qualifier.