A sexual harassment case was filed against Orissa Assembly Speaker Maheshwar Mohanty on Thursday by a woman security staff whose allegations rocked the House for the second day today with Opposition members storming the presiding officer's podium.

The First Information Report was filed in the Mahila police station in Bhubaneswar by a group of women activists on behalf of Gyatri Panda, the assistant marshal, as she was not present there, a day after she accused Mohanty of sexual harassment.

Accusing the apeaker of engaging his staff to persuade her to have sexual relations with him, the FIR alleged that Mohanty often made vulgar gestures at her.

Mohanty has denied the charges claiming it was part of a conspiracy in which influential people were involved to malign him.

Panda alleged that some anti-social elements gave her a life threat after she levelled the charges against the speaker in public.

The controversy sparked unprecedented scenes in the assembly as Opposition members, demanding Mohanty's resignation, laid a siege at the podium preventing Deputy Speaker Prahallad Dora from reaching the chair.

Mohanty had expressed his desire not to preside over proceedings until he emerged clean after a probe by a House committee.

At a news conference, Chief Minister Naveen Patnaik rejected the Opposition demand for Mohanty's resignation and an impartial probe by an independent agency.

"I want the inquiry to be conducted by honourable members of the House and not by any external agency," he said.

The Women's wing of the state Congress staged a demonstration and burnt Mohanty's effigy in Bhubaneswar demanding that he quit office.