Accusing the government of trying to "hush up" the case relating to the mysterious death of an upright IAS officer, Opposition parties on Wednesday sought Karnataka Governor's intervention for a CBI probe into the incident that has sparked outrage and protests in the state.

BJP and JDS MLAs marched from Vidhana Soudha, the state secretariat, to Raj Bhavan and told Vajubhai Vala that there were "vested interests", politicians and "big people" behind the incident and only a CBI probe can bringing out the truth.

"We have petitioned him that this mysterious death should be investigated only by CBI. We have told him that with an intention to hush up this issue government is not willing to hand over this issue to CBI," Opposition BJP leader in the Assembly, Jagadish Shettar told reporters.

Alleging that the government was indulging in character assassination of the officer D K Ravi, Shettar said "the Chief Minister's remarks in an interview to a paper reflects the clear intentions of the government. A Chief Minister speaking about the personal life of D K Ravi clearly shows where they are taking this issue."

He also questioned government's action in transferring Pranab Mohanty, who was the Inspector General of CID, which has been handed over the case for investigation, to the Lokayukta's office.

Charging that the government was trying to hush up the case, Shettar said "there is vested interest behind this case, politicians and big people are behind this. Truth behind this mysterious death has to come out. Hence we are demanding a CBI inquiry and we have apprised the Governor about it."

He said they have told the Governor that he should direct the state government to hand over this case to CBI.

"Governor has promised to look into this issue and he has said he will do what ever possible with the frame of law."