<h1>Codeine-based cough syrup crackdown prompts calls for central probe and fuels political dispute over alleged links.</h1> Dhananjay Singh rejected a 'Codeine Bhaiya' jibe and called for serious investigation into alleged over-stocking, interstate illicit manufacture and distribution of codeine-based cough syrups and potential money laundering, urging involvement of central agencies such as the CBI and the Enforcement Directorate; he denied personal involvement in narcotics trade and distinguished the UP syrup matter from a separate Madhya Pradesh case.