Ghana midfielder Kevin Prince Boateng has retired from international football saying he wants to concentrate on AC Milan.The 24-year-old has told the Ghana FA of his decision to quit the World Cup quarter-finalists.The German-born switched nationality to play for Ghana just before last year's World Cup in South Africa.He played nine matches for the Black Stars and scored one goal.The Ghana Football Association says it received a letter from Prince Boateng on his decision to resign from the senior national team, the Black Stars.According to Kevin, the physical demands of playing for both club and country at high levels are taking a toll on his health.The player also explained that in order to remain healthy and stay off any injuries, he has consulted his doctors and family over the matter and has decided to take the decision to excuse himself from national duties since he is on a special training that he has to interrupt to honour national invitations.The Ghana Football Association is yet to take a position on the decision of Kevin Prince Boateng.