A BJP delegation on Monday wrote to Calcutta Police Commissioner Soumen Mitra alleging that an illegal exercise was being carried out in the force to "enable collection of postal ballot and effect proxy votes" during assembly elections, set to begin on March 27.

In the letter undersigned by BJP MP Swapan Dasgupta and senior leaders Sabyasachi Dutta and Shishir Bajoria, the party claimed that a section of police officers, under the banner of Welfare Association, is collecting photocopies of voter and Aadhaar cards of their colleagues across all ranks as part of the operation.

The saffron party also said that it was a "highly irregular act and also tantamount to taking away someone's fundamental right to vote".

It said that an "inspector by the name of Santanu Sinha Biswas is spearheading the exercise and two sub- inspectors Tapan Kr Maity and Bijitaswo Raut are assisting him, among others".

The BJP leaders further stated in the letter that several "serving police personnel were seen swearing allegiance to Trinamool Congress in the presence of party MP Subrata Bakshi" at Uttirno building in Alipore on February 13.

The party demanded that an enquiry be carried out in the matter, and the police personnel carrying out the "illegal exercise" be immediately suspended.

It sought necessary steps to stop the operation, as it "comes under the provisions of Corrupt Practices in the Representatives of People's Act".

Last week, the BJP had lodged a complaint with the Chief Electoral Officer of Bengal against some police officers, who, the party claimed, were resorting to unfair means to prevent free and fair polls in the state.