Daring the BJP to impose President's Rule in West Bengal, Mamata Banerjee called it a "total constitutional breakdown". "How dare you come to a police commissioner's home without a warrant? Mr (Ajit) Doval is doing whatever PM wants him to do, he is the one giving all the instructions to CBI," Ms Banerjee said, referring to the National Security Advisor.

"This is a Satyagraha and I'll continue till the country is saved," Ms Banerjee said. She spent the night at the designated spot for protests in central Kolkata, accompanied by city police chief Rajeev Kumar. Ms Banerjee skipped meals and remained awake the entire night as she sat on the makeshift dais. She will proceed to the assembly later this morning for the state budget. "We have full confidence in the judiciary, media and the people... If they want to impose President's Rule, we are ready for it," she said.

The CBI is expected to go to the Supreme Court today, accusing the West Bengal government of impeding a court-ordered probe into the chit fund scams, said the agency's interim boss, M Nageswara Rao. The state government is also likely to appeal to the top court about the issue. The CBI officials are planning to meet West Bengal Governor Keshari Nath Tripathi.

Rajeev Kumar - who headed a Special Investigation Team probing the Saradha and Rose Valley Ponzi scams of 2013 - was asked to help the investigation after several documents allegedly went missing. He has received several summons for questioning. This time, a section of media reported that he could be arrested for evading questioning and was "absconding". The Kolkata Police said they would take action for the defamatory reports.

Senior Trinamool leader Derek O'Brien said on Sunday evening, 40 CBI officers turned up at the Park Street House of Rajeev Kumar. But they were refused entry by the police guards posted there and the team was taken to a local police station. Ms Banerjee and top police officers held an emergency meeting at Mr Kumar's house.

Accusing the BJP of engineering the crisis, Ms Banerjee said the trouble flared up after her mega rally of 23 opposition parties in Kolkata last month. "The Kolkata Police Commissioner is among the best in the world. His integrity, bravery and honesty are unquestioned. He is working 24x7, and was on leave for only one day recently. When you spread lies, the lies will always remain lies," she tweeted.

The chief minister also accused PM Modi of using unparliamentary language during his recent rallies in the state. The Prime Minister had claimed the West Bengal government was killing the aspirations of the middle class through "Triple T - Trinamool Tolabazi Tax". 'Tolabazi'' roughly translates to an act of organised extortion.

The state's BJP lawmaker Babul Supriyo tweeted: "President's Rule should be imposed on West Bengal to control this 'Rogue' #TMchhi Govt under a corrupt CM MamtaBanerjee. This is a constitutional crisis 'created' by Mamta to shield her corrupt & tainted accomplices (sic)".

The opposition has rallied around Ms Banerjee, with various leaders -- including Arvind Kejriwal, Tejashwi Yadav, Lalu Yadav and HD Deve Gowda tweeting their outrage. Mr Kejriwal, Omar Abdullah and Congress chief Rahul Gandhi called up Mamata Banerjee and offered her full support. Several opposition leaders are likely to visit her today.