Congress President Sonia Gandhi and former prime minister Manmohan Singh on Monday visited Tihar jail to meet their jailed party colleague and former FM P Chidambaram. The senior Congress leader is under arrest since a month in the INX media alleged corruption case. Chidambaram’s son and co-accused in the case Karti also met him on Monday. Chidambaram first spent 2 weeks in the CBI custody and then was shifted to Tihar jail. A Delhi court had last week extended his custody till October 3.