A plan is on to have Chief Ministers of all like-minded parties to sit on a protest at Delhi's Jantar Mantar over the alleged attack on the country's federal structure, sources said. The tentative date is February 12.

"We spoke to Sharad Pawar, Arvind Kejriwal, Sharad Yadav etc. Everybody has arrived at a consensus that Mamata Banerjee should end this dharna. We will take up this issue in Delhi," Chandrababu Naidu said.

This morning, the Supreme Court said Kolkata police chief Rajeev Kumar should appear before the Central Bureau of Investigation in Meghalaya's Shillong on February 20. He should submit all evidence and cooperate with the probe into chit fund scams in Bengal, the court said.

The CBI contended that Mr Kumar, who conducted the initial investigation into the Saradha and Rose Valley Ponzi schemes, had "doctored evidence" to shield the accused. Several leaders of Mamata Banerjee's Trinamool Congress have been arrested in the case.

The Centre has ordered the Bengal government to begin departmental proceedings against Rajeev Kumar for breaking service rules and disciplinary code.

The CBI went to the Supreme Court on Monday - a day after their team which went to question Rajeev Kumar at his home in Kolkata was stopped and detained by the police.

Shortly after the showdown, the furious Chief Minister had launched her indefinite dharna, accusing the BJP of using the CBI for "political vendetta" and calling it a "constitutional breakdown".

Hailing the top court's order on Tuesday as a victory of the Constitution, Mamata Banerjee said: "They wanted to arrest him. They went to his house on a secret operation, without any notice. That court said 'no arrest', we are so obliged".

Mr Naidu was the third opposition leader to reach Kolkata to show solidarity with Ms Banerjee. On Monday, Tejashwi Yadav, the son of Bihar's veteran leader Lalu Yadav and DMK's Kanimozhi had reached Kolkata and shared stage with the Chief Minister.