“Let me make it very clear,” said Arindam Bagchi, the spokesperson of India’s Ministry of External Affairs, to a group of gathered reporters. “We think this is a propaganda piece designed to push a particular discredited narrative. The bias, the lack of objectivity and, frankly, the continuing colonial mindset is blatantly visible.”

The undiplomatic language from an experienced diplomat was striking because he was referring to a BBC documentary about events from decades ago in one of India’s 28 states, albeit events that leave a deep, abiding and likely indelible stain on the reputation of Prime Minister Narendra Modi. Part One of the documentary — “India: The Modi Question” — was broadcast in the U.K. on January 17, and Part Two was broadcast a week later. Neither part has been screened in India.

Invoking “emergency” powers, India has blocked even the sharing of links to clips from the documentary on social media. On January 21, before Part 2 had been screened in the U.K., Kanchan Gupta, a former journalist and the senior advisor to the Ministry of Information and Broadcasting, described the documentary in a tweet as “hostile propaganda and anti-India garbage,” as he announced the decision to block tweets and links “under India’s sovereign laws and rules.”

What so incensed the Indian establishment was the documentary’s revelations that a British government inquiry into communal riots in Gujarat in 2002 held Narendra Modi, then chief minister of Gujarat, “directly responsible” for enabling three days of horrifying violence. The riots resulted in the deaths of a thousand people — nearly 800 of them Muslim, according to official figures.