Calcutta: Those who believe that every Bengali is a Bangladeshi to the BJP and its governments have got the chance to cry “documentary proof”.

The Trinamool Congress has circulated images of a communication carrying the Delhi Police letterhead that refers to the Bengali language as “Bangladeshi language” and “Bangladeshi national language”.

The Delhi Police report to the Union home ministry.

The letter — coming amid detentions and alleged torture of migrant Bengali labourers in BJP-ruled territories — prompted outrage across Bengal’s political spectrum except for the state BJP.

Mamata Banerjee countered the “Bangladeshi national language” claim by underlining that India’s national anthem was written in Bengali.

A Delhi Police station house officer appears to have written the letter to Banga Bhavan, requesting a translator for eight people arrested on suspicion of being illegal Bangladeshi immigrants. Senior police officers in Delhi told this newspaper they had no knowledge of the letter.

The Bengal chief minister, spearheading a “language movement” against the BJP’s “language terror” in the run-up to next summer’s Assembly polls, pounced on the letter.

“See now how Delhi police under the direct control of Ministry of Home, Government of India is describing Bengali as ‘Bangladeshi’ language!” she said in a post on X.

“Bengali, our mother tongue, the language of Rabindranath Tagore and Swami Vivekananda, the language in which our National Anthem and the National Song (the latter by Bankim Chandra Chattopadhyay) are written, the language in which crores of Indians speak and write, the language which is sanctified and recognised by the Constitution of India, is now described as a Bangladeshi language!!”

Mamata urged “immediate strongest possible protests from all against the anti-Bengali Government of India who are using such anti-Constitutional language to insult and humiliate the Bengali-speaking people of India”.

The letter, to the officer in charge of Banga Bhavan in Delhi, is purportedly signed by inspector Amit Dutt of the Lodhi Colony police station.

The letter refers to FIR number 51/2025, and its subject line says: “Translation of documents containing text written in Bangladeshi language-regarding.” The date could not be ascertained.

“During the course of investigation, eight (08) persons strongly suspected to be Bangladeshi nationals residing illegally in India without any valid passport or visa, were arrested…,” the letter says.

“The identification documents contain texts written in Bangladeshi and are needed to be translated to Hindi and English,” it adds.

“...It is requested that an official translator/ interpreter proficient in Bangladeshi national language may kindly be provided for the aforesaid purpose.”

Bengali, or Bangla, is an official language in Bengal and the mother tongue of millions in Assam and Tripura, too. It’s the second-most widely spoken language in India, after Hindi. Last year, the Centre put Bengali on the list of “Classical Languages of India”.

Mamata’s nephew and heir apparent Abhishek Banerjee demanded Dutt’s immediate suspension and a public apology from the Delhi Police, BJP and the Union home ministry.

“It is a direct violation of Article 343 and the Eighth Schedule of the Constitution…. To call Bangla a foreign language is not just an insult — It’s an attack on our identity, culture and belonging,” he said.

The CPM wondered whether, by this logic, Tamil would now be labelled a Sri Lankan language, or Punjabi a Pakistani language.

“What exactly is the Bangladeshi language? The home ministry and the Delhi Police must explain,” CPM state committee member Shatarup Ghosh said.

“Indians speaking in Bengali are Bangladeshi because they speak in their mother tongue? This is akin to the heinous persecution of people from the Northeast as ‘Chinese’ in Delhi.”

The state Congress condemned the BJP while underscoring that these gaffes tend to favour Mamata alone.

Condemning the persecution of Bengali-speaking Indians in BJP-ruled states, the Congress’s chief spokesperson in Bengal, Soumya Aich Roy, said he was at a loss for words “in attempting to describe what a heinous crime this is”.

“But why are millions of people compelled to go and look for employment opportunities in other states, despite Mamata Banerjee, with all her lofty claims of economic uplift, having been chief minister for 14 years?” he asked.

“The BJP is helping her turn this into an issue here, to commodify it as a plank to retain power.”

Former state BJP chief Sukanta Majumdar, currently a junior Union minister, said he was yet to go through the controversial letter but added that there was no denying that Bengali was Bangladesh’s language as well.

“Hence, there was nothing technically wrong…. There are many differences between their language and ours, which woke liberal intellectuals here vehemently dismiss,” Majumdar said.

Some of the regional dialects spoken in Bangladesh are significantly different from those prevalent in Bengal, but the language itself is considered the same on both sides of the border.

Majumdar added: “Let Mamata Banerjee speak correct Bengali first. To begin with, she cannot speak the language properly.”

Political watchers wondered whether the RSS-BJP was at all serious about ousting Mamata from power, given its cavalier way of handing her one emotive issue after other by repeatedly putting its foot in its mouth since the 2021 election campaign.

“Such activities are true to the Hindi-Hindu-Hindustan line of the Sangh Parivar’s hard-line Hindutva that the BJP represents and promises,” political scientist Subhamoy Maitra said.

“Having said that, vast sections of the middle and upper socioeconomic classes of Bengal were immensely displeased with the corruption and criminalisation under Trinamool, the RG Kar brutality, the state of education, etc, and could have swung away from her,” he added.

“Those sections are being turned against the BJP by none other than the BJP. There can be only one logical inference: the RSS lacks confidence in the BJP’s abilities here, and prefers Mamata as a placeholder in Bengal to keep the Left from clawing back…. Otherwise, this degree of being casually callous is inexplicable.”

Additional reporting by our Delhi bureau