West Bengal Chief Minister Mamata Banerjee has been staging a dharna to save the 'federal structure' from Sunday night. She began the 'Save the Constitution' dharna after a team of Central Bureau of Investigation (CBI) moved to arrest Kolkata Police Commissioner Rajeev Kumar.

According to reports, the Commissioner was to be questioned regarding missing documents and files but he is not responding to notices to appear before the agency. Kumar was heading a SIT on the Saradha and Rose Valley scams.

Meanwhile, continuing the dharna, Mamata Banerjee informed media that a memorandum has been signed by all the Opposition parties which will be submitted to the Election Commission later in the day.

On the other hand, the CBI is set to approach the Supreme Court on the matter alleging 'non-cooperation' by Kolkata Police.