Tensions have flared at two of India's best-known universities over the screening of a BBC documentary on Prime Minister Narendra Modi and his role in deadly religious riots in 2002.
Police detained about a dozen students at Jamia Millia Islamia university in Delhi ahead of a planned screening.
On Tuesday students at another Delhi university said power and internet had been cut to stop them showing the film.
India's government says the documentary lacks objectivity and is "propaganda".
It has invoked emergency laws to block the documentary on YouTube and Twitter.
Dozens of police personnel wearing riot gear were deployed at Jamia university, whose officials said they would not allow any "unauthorised gatherings".
A BBC Hindi reporter at the campus said the university's gates had been locked and described the atmosphere inside as calm. There was, however, a huge crowd of students and journalists outside. Videos showed dozens of police personnel standing in a line outside the locked gate.
It comes hours after trouble at Jawaharlal Nehru University (JNU) in Delhi on Tuesday night. Students there accused officials of cutting off power and internet supply to stop a screening. There was no immediate response from university officials to the allegation.
The university administration had asked the JNU students' union not to screen the film, saying it could "disturb the peace and harmony of the university campus".
Although the power cut prevented the public screening, JNU student leaders distributed QR codes so people could stream the video on their laptops and phones.
There was a heavy police presence on that campus too. While students were watching the documentary, stones were thrown at them by "a group of 20-30 people", our reporter said. Students say they have filed a police complaint.
The first episode of India: The Modi Question - a two-part series - aired in the UK on 17 January. The second part was broadcast on Tuesday.
India's foreign ministry has criticised the documentary, calling it "a propaganda piece designed to push a particular discredited narrative".
But the BBC has said the film was rigorously researched. A BBC statement said the series examines "the tensions between India's Hindu majority and Muslim minority and explores the politics of Mr Modi in relation to those tensions". It added that the Indian government was offered a right to reply, but had declined.
The first episode of the documentary tracked Mr Modi's first steps into politics, from his rise through the ranks of the Bharatiya Janata Party (BJP) to his appointment as chief minister of the western state of Gujarat.
It highlighted a previously unpublished report, obtained by the BBC from the UK foreign office, which raises questions about Mr Modi's actions during the religious riots that broke out in Gujarat in 2002 after a train carrying Hindu pilgrims was set on fire, killing dozens. More than 1,000 people, mostly Muslims, died in the violence, some of the worst seen in India since Independence in 1947.
The report claims that Mr Modi was "directly responsible" for the "climate of impunity" that enabled the violence.
Mr Modi has long rejected accusations that he had any responsibility for the violence and has not apologised for the riots. In 2013, a Supreme Court panel ruled there was insufficient evidence to prosecute him.
Although the BBC documentary was not aired in India, several opposition leaders and government critics shared links to it on social media.
An adviser to India's government said it had ordered Twitter to block tweets linking to the film, while YouTube had been instructed to block uploads of it.
Twitter confirmed to the BBC that it had blocked 50 tweets based on a request by India's ministry of information and broadcasting on 20 January under the country's information technology law.
A YouTube spokesperson said the video had been "blocked from appearing by the BBC due to a copyright claim". A BBC spokesperson said: "As is standard practice, we follow procedure to have illegal uploads of any BBC content removed."
The JNU students' union has said it will hold another screening of the documentary. Several other Indian organisations have also held screenings in recent days or announced plans to do so.