The CBI Friday registered cases against three current and three former Rajya Sabha members in what has come to be termed as the leave and travel concession (LTC) scam, an official said.The three sitting MPs are Lalhming Liana of the Mizo National Front (MNF), D. Bandyopadhyay of the Trinamool Congress, and Brajesh Pathak of the Bahujan Samaj Party. The former MPs named in the case are Bharatiya Janata Party's (BJP) J.P.N. Singh, Rashtriya Lok Dal's (RLD) Mahmood A. Madani, and Biju Janata Dal's (BJD) Renubala Pradhan, the CBI official said.This is the first case registered by the Central Bureau of Investigation (CBI) in the scam.According to the agency, searches are being conducted at 10 locations, which include the houses, office premises of the MPs and also at the offices of travel agencies in Delhi and Odisha.Lakhs of rupees are said to have been fraudulently claimed from the government through fake leave and travel concession (LTC) claims, availed by government officials to get concessional tickets.The incident came to light after the vigilance department of Air India (AI) was alerted about the arrest of a man in March at the Kolkata airport with 600 blank boarding passes of the airline in his possession.