The Delhi Police on Wednesday sternly opposed a plea for a CBI probe into death of Constable Subhash Tomar, saying a third-party "intervention" shouldn't be allowed in a criminal case.

The constable had died in mysterious circumstances during the massive protests at India Gate following the December 16 gang rape in south Delhi.

"The petitioner is a lawyer. He is neither an accused nor a witness nor the complainant in the case," additional solicitor general (ASG) Siddharth Luthra, appearing for Delhi police, submitted before justice GP Mittal.

The court was hearing a public interest litigation filed by lawyer Gaurav Bansal.

Luthra said a controversy was triggered by versions of two eyewitnesses, two contradictory conclusions by Ram Manohar Lohia Hospital and the hospital's post-mortem report on the exact cause of the constable's death.