The Enforcement Directorate (ED) has summoned Karti Chidambaram, son of senior Congress leader P Chidambaram, for questioning in connection with its money laundering probe in the INX media case. <br/><br/>Official sources said Karti has been called on 11th of this month. <br/><br/>The agency had registered a case against Karti and others in May last year under the provisions of the Prevention of Money Laundering Act.