Officials of the income tax department arrived at the offices of the BBC in Delhi and Mumbai on Tuesday morning for a “survey”, weeks after the British broadcaster had screened a documentary critical of Prime Minister Narendra Modi.

The synchronised action began at 11am with the tax officials reaching the offices on KG Marg in New Delhi and Santacruz in Mumbai and sealing them off for the “survey” that was still continuing till late in the night.

The tax department had on Tuesday not issued any statement on the reason for the searches, which were condemned as a sign of “undeclared Emergency” by the Opposition that contrasted the action with the government’s refusal to investigate the Adani group whose shares crashed following allegations of accounting fraud and stock manipulation.

The London-headquartered BBC said on Twitter at 2.49pm: “The Income Tax authorities are currently at the BBC offices in New Delhi and Mumbai and we are fully co-operating. We hope to have this situation resolved as soon as possible.”

At night, the BBC said: “The Income Tax Authorities remain at the BBC offices in New Delhi and Mumbai. Many staff have now left the building, but some have been asked to remain and are continuing to cooperate with the ongoing enquiries.

“We are supporting our staff during this time and continue to hope to have this situation resolved as soon as possible. Our output and journalism continues as normal and we are committed to serving our audiences in India.”

BJP spokesperson Gaurav Bhatia described the BBC as the world’s “most corrupt” corporation and said: “India is a country which gives an opportunity to every organisation, as long as you don’t spew venom.” He accused the BBC of a “hidden agenda” in its reporting and said: “This cannot be tolerated.”

The BBC has been under fire from the BJP and the Modi government ever since the documentary, India: The Modi Question, came out last month. The government had blocked the film, which examines Modi’s role during the 2002 Gujarat riots, on social media.

On January 20, amid the protests, the BBC stood by its reporting and added: “BBC staff in India were not involved in the making of these programmes. This documentary was commissioned by BBC Current Affairs based in the UK and intended for a domestic audience.” The statement was seen as an attempt to shield its employees in the country from possible retaliation.

“Here we are asking for Joint Parliamentary Committee (JPC) probe into the Adani-Hindenburg issue and there the government is hounding BBC. Vinash Kale Viprit Buddhi,” Congress leader Jairam Ramesh said in a tweet on Tuesday.

Trinamul Congress MP Mahua Moitra tweeted: “Reports of Income Tax raid at BBC’s Delhi office. Wow, really? How unexpected. Meanwhile farsaan seva for Adani when he drops in for a chat with Chairman @SEBI_India office.”

“Since agencies doing these Valentine Day ‘Surveys’ how about @IncomeTaxIndia, @SEBI_India & @dir_ed conduct one on govt’s most valued sweetheart Mr A?” she added.

Britain’s Foreign Office said it was closely monitoring reports of tax surveys conducted at the BBC’s offices.

The searches came on a day the Union home minister said in an interview to ANI about the BBC documentary that Modi has been targeted since 2002 but comes out stronger and more popular each time.

Sources said the BBC employees were asked to deposit their mobile phones and laptops/desktops and not to call anyone from the landline nor leave the premises.

A video shared on social media shows a man in a yellow check shirt and jacket loudly saying: “Income tax department.” A woman’s voice is heard saying: “They are from the IT department.” The man continues, gruffly: “Chalo aaplog phone rakho idhar.” The woman who can’t be seen in the clip says: “Aaram se toh baat karo Bhaiya.” There is an exchange as the man asks why they were kept waiting while the woman asks how they could be allowed in without first seeing the warrant. A man who has his back to the camera is seen motioning to the woman to let it be.

Sources in the tax department insisted that this was not a raid but a survey. “Our team visited the two BBC offices to carry out a survey. They went there to seek some clarifications and to check account books and asked the BBC’s finance department for details of balance sheets and accounts,” a source in the IT said.

“As part of a survey the IT officials only cover the business premises of a company and do not raid residences and other locations of its promoters/directors,” an IT official told The Telegraph.

Last week the Supreme Court had dismissed as “completely misconceived” and “absolutely meritless” a petition by the Hindu Sena seeking a ban on the BBC in India and an NIA probe into the British broadcaster’s alleged anti-India activities.

On Friday the apex court had also directed the central government to produce original records relating to its decision to block the BBC documentary.

The matter was listed for next hearing in April.