Panic spread among several people across Bengal after they received letters from the UIDAI informing them that their Aadhaar number had been deactivated and their requirements to stay in the country were not fulfilled.

The UIDAI or Unique Identification Authority of India is responsible for issuing and deactivating the Aadhaar card—a mandatory document for a citizen of India.

Chief minister Mamata Banerjee, on the floor of the Assembly during her budget speech on Thursday, said that she had received such complaints of Aadhaar deactivation.

"They (the BJP) are deactivating Aadhar cards so that these people can't cast their votes. Several MLAs and MPs, especially from North 24-Parganas, complained to me about such deactivation of the Aadhaar card of many people. I have asked my administration to look into such allegations," she said.

The letter sent to a woman in East Burdwan reads: "The undersigned is directed to inform that Aadhar number XXXX issued to you has been deactivated under the provisions of regulation 28A of Aadhar (Enrolment and Update) Regulations, 2016, for the reason the requirements for your stay in India are not fulfilled."

According to the UIDAI website, regulation 28A of Aadhaar (Enrolment and Update) Regulations, 2016, is a provision to deactivate the Aadhar for foreign nationals whose period of validity of visa for stay in India has expired or for any person ho has not fulfilled the requirements for their entry to or stay in the country under the Passport (Entry into India) Act, 1920 (34 of 1920). The guidelines are issued by the ministry of home affairs in this regard from time to time.

The letter, issued by its Ranchi office in Jharkhand, asked this woman to contact any of the UIDAI's regional offices if the Aadhaar number holder has any complaints.

An official in the Ranchi regional office of the UIDAI admitted that they had issued around 1 lakh such letters across the country.

"The letters have been sent to those whose Aadhaar number has raised doubts for many reasons. We have so far issued around a lakh such letters to different persons across the country" said the UIDAI official.

Putul Sarkar, a resident of Juthihati village of East Burdwan's Jamalpur, who received one such letter, said she was scared.

"I am really afraid after receiving this letter of deactivation of my Aadhaar number. I doubt if I would be able to operate my bank accounts," she said, asking if she was still a citizen of India.

Sajahan Mondal, deputy chief of Jaugram gram panchayat in Jamalpur, said that at least 20 people in his area received such letters from the Aadhaar authority.

"Since then, many people have complained that they could not draw their ration because their biometric was not recognised in the Aadhaar-enabled system. We have already contacted our local administration seeking assistance as all those who have received such letters (deactivating Aadhaar) are from very poor families," said Mondal.

A source said the Trinamul dispensation was closely monitoring the developments.

Trinamul candidate for the Rajya Sabha and Matua community leader Mamata Bala Thakur said she has received complaints from districts that hundreds received such letters.

"I received complaints from Nadia and North 24-Parganas, among others. I fear whether this is the first step towards implementing the NRC or the CAA. Deactivation of Aadhaar means people can't get government benefits or vote. We will raise our voice against such a practice," she said.