(Corrects date of board meeting to May 25, not May 24)

SAO PAULO, Oct 5 (Reuters) - Brazilian steelmaker Companhia Siderúrgica Nacional said on Wednesday a court ruling that annulled the appointment of a new chief executive at Usinas Siderúrgicas de Minas Gerais SA was the result of a shareholder dispute that was harming the company.

In a statement sent to Reuters, CSN said the decision by a regional court in Minas Gerais to annul the decisions of a May 25 meeting of Usiminas' board was "the fallout from an insane fight among the controllers of Usiminas, which is prejudicial to the company and its shareholders." (Reporting by Ana Mano; Editing by Daniel Flynn)