The CBI has registered a Preliminary Enquiry (PE) against unknown officials of Defence Ministry and others to probe alleged kickbacks in Embraer aircraft deal.<br/><br/>Earlier, the government had asked the CBI to probe allegations of Brazilian aviation major Embraer hiring a UK-based agent and paying commissions to swing the deal for three Emb-145 aircraft signed with India in 2008. The three EMB-145 aircraft have been equipped with indigenous radars in a 2,520 crore rupees DRDO project to serve as airborne early-warning and control systems aircraft for Indian Air Force.