The central Bureau of Investigation (CBI) has not registered a case on a complaint of the home ministry seeking a probe into the alleged violation of Foreign Contribution Regulation Act by some NGOs due to legal and technical issues. Sources in the CBI said there were many such issues which need to be sorted out before a decision can be taken on whether to file a preliminary inquiry or regular case. They said the complaint about alleged contravention of the provisions of FCRA, 2010 against two Tamil Nadu-based NGOs was being examined by the legal experts as well. The ministry referred two cases of FCRA violation to the CBI last week and two cases to Tamil Nadu police. Bank accounts of these four NGOs were frozen after an inquiry conducted by the home ministry reportedly found them diverting funds meant for charity to fuel the protests.