The showdown started after the federal probe agency's officers showed up near the residence of Kolkata police commissioner Rajeev Kumar, who has been under the scanner in connection with the CBI probe into the ponzi scheme scam case.

On Saturday, CBI sources said they were "looking for" Kumar, a 1989 batch IPS officer, and even claimed that he might be arrested if he failed to respond to the CBI's summons.

On Sunday, the evening drama began in front of Kumar's official residence on Loudon Street as a group of CBI officers approached the house, but they were stopped by city police personnel, who also forcibly took five federal probe agency officers to a police station.

The Chief Minister, who had extended support to Kumar earlier in the day, also rushed to his house and was closeted with other top officers, including state police Director General Virendra.

A visibly angry Banerjee came out of Kumar's residence after over an hour, and alleged that National Security Advisor Ajit Doval was giving instructions to the CBI at the behest of Prime Minister Narendra Modi and BJP President Amit Shah.

She announced she would begin a sit-in at the city hub Dharamtala.

"I am sorry to say National Security Advisor Ajit Doval is giving instructions to the agency. He is implementing what PM Narendra Modi is asking for. He should tell the people that it is not correct," an agitated Banerjee said.

"I will start a dharna (sit-in) at Dharamtala area to save institutions, Constitution and the federal structure of the country," she said.

Minutes later she began the sit-in, as the police commissioner also joined her at Metro Channel.

Banerjee said a meeting of the state cabinet would be held on Monday at the venue of sit-in to ratify the state budget which would be presented during the day.

She said Assembly proceedings would continue as usual.

Banerjee also alleged CBI officers came to Kumar's residence without any search warrant to conduct a secret operation.

"You are coming to the commissioner's residence without any warrant to conduct a secret operation. It is (nothing but) instruction from Narendra Modi and Amit Shah.

"How can they come? One day, they will go to my home, Chief Secretary's home and Home Secretary's home. There is a constitutional break-down and they are trying to run a parallel administration in the states," she told reporters outside the Commissioner's house.

"I have come here because I have a constitutional responsibility to give protection to the forces and it is my personal responsibility. Even, it is our government's responsibility. I will stand by our forces in the state as well as other security forces of the country. If the chief of an organisation is humiliated, how will it work?"

Banerjee appealed to all security forces to be together and condemn the attitude of the Modi government.

She called the developments a 'blow' to the country's federal structure, and claimed that the Supreme Court in its judgement had said both central and state agencies can discuss mutually if they have any queries.

"Subsequently, CBI went to Supreme Court issuing notices and the apex court suggested they go to the Calcutta High Court, which has issued a stay order on the CBI notices. Despite that, CBI officers came to CP's residence to conduct the secret operation," she said, and remarked that a "super emergency" has been clamped on the country.

"They are hatching a conspiracy to heckle everyone. They are trying to control even the media. Governors' houses across the states have become BJP's party offices," she added.

The CBI officers, led by its deputy superintendent Tathagata Bardhan, were spotted near Kumar's residence around evening, but within a few minutes some senior Kolkata police officers rushed near the residence and were seen having animated discussions with the CBI team.

A little later, another CBI team reached the spot in another car, while Bardhan contacted his higher-ups and said "no" when asked if they were retreating from the spot.

Meanwhile, a strong city police team was seen near the CBI's state headquarters at CGO Complex in the Salt Lake area. However, they left after a couple of hours.

The drama intensified near Kumar's residence around 7 p.m., as three deputy commissioners of city police and some officers of the anti-rowdy section reached the spot, following which there ensued a scuffle between the CBI team and cops.

The five CBI officers including Bardhan were bundled into three vehicles and taken to the Shakespeare Sarani police station.

The CBI officers were released later in the night.

Meanwhile, the Central Reserve Police Force troops were deployed at the CBI headquarters.

Trinamool spokesperson and Rajya Sabha MP Derek O'Brien wondered whether the BJP was planning a 'constitutional coup' and said his party would raise the matter in Parliament on Monday.