Mr Radhakrishnan made the statement after the Opposition created ruckus in the Assembly over Dharmarajan's statement that Congress leader PJ Kurien was among those who raped the 16-year-old school girl in 1996.
In 2005, the Kerala High Court acquitted 34 men of the rape of the teenager from Suryanelli in Kerala. A lawyer named Dharmarajan was convicted. He was sentenced to five years in prison and was granted bail after which he went underground.
He said in an interview to regional TV channel Mathrabhumi yesterday that in 1996, he drove Mr Kurien, who is the Vice Chairman of the Rajya Sabha, to the guest-house where the gang-rape survivor says she was assaulted by Mr Kurien.
Dharmarajan said that at the time, he was pressured by the Kerala Police not to testify against the Congressman.
Mr Kurien has been exonerated by the Supreme Court; he was not among the 35 men tried for the woman's rape by the Kerala High Court. But over the last few days, the rape survivor has reiterated that the police did not investigate Mr Kurien long or hard enough because of his political clout.
Her allegations have been made after the Supreme Court set aside the Kerala High Court's order, and asked for a retrial of the rape case to be completed within six months.
The Congress has said that before Parliament convenes on February 21, it will decide whether Mr Kurien should be removed from his Rajya Sabha office.
Last week, in an interview to NDTV, Mr Kurien said the charges against him are a political ruse and that multiple police investigations have cleared him in the case.
"I am the one who has been wronged. My conscience is clear and the case is a political one," he said.