The alleged episode had brought disrepute to the entire state of Tamil Nadu, DMK leader MK Stalin said.
Tamil Nadu's main opposition party DMK as well as the PMK denounced the transfer of a senior Crime Branch-CID officer in a "hurry", soon after the case of alleged sexual scandal involving a college professor was transferred to it.
The parties reaffirmed their demand for a CBI probe in the case of alleged misconduct by Nirmala Devi, an assistant professor at Devanga Arts College in Virudhunagar district who was
alleged to have prodded students to extend sexual favours to officials of the Madurai Kamaraj University for better marks and money.
DMK Working President MK Stalin said just after ordering the transfer of the case to the Crime Branch-CID, the government shifted the unit's Additional Director General of Police K Jayanth Murali in a hurry.
The alleged episode had brought disrepute to the entire state of Tamil Nadu, he told reporters.
"Who are involved in this case and who are behind it? If this has to be ascertained, and for the truth to emerge, the probe has to be done by the CBI under the supervision of the high court," he said.
"A conspiracy is on to bury this case," PMK founder leader S Ramadoss said and added that the transfer of the senior official within 24 hours of handing over the case to the CB-CID was "shocking".
"All the bigwigs in the sexual scandal can be exposed only by a CBI probe and this is essential for the parents in Tamil Nadu to send their children to schools and colleges without fear," he said.
A state minister said that the government would take action against the accused professor.
On 16 April, Aruppukottai-based Devanga College assistant professor Nirmala Devi was arrested by police, a day after an audio clip went viral in social media where she purportedly sought to persuade girls to consider extending sexual favours to senior university officials.
The case, initially registered by the local police, was transferred to the CB-CID on April 17 because of its "sensitive nature", according to Director General of Police TK Rajendran.
K Jayanth Murali was transferred to Vigilance and Anti-Corruption wing as ADGP/Director on April 18. He was replaced by Amaresh Pujari, ADGP-Crime.
Secretary of the college Ramasamy had said on April 16 that Nirmala Devi was placed under suspension after a preliminary inquiry by three professors of the college.
The assistant professor was purportedly heard saying in the audio clip that she knew Governor Banwarilal Purohit and had access to him. Mr Purohit, however,
rejected her claim recently and said he had not even seen her.