Indian police have detained two schoolboys accused of repeatedly beating a low-caste classmate for getting good grades, an officer said Wednesday, with a video of the attacks going viral.

The 16-year-old from India's lowest Dalit caste released a letter to a national television network pleading for the violence to stop, after the video of him being punched and kicked in a classroom made headline news.

The beatings, which the boy says took place every day for two years, are the latest incidents of violence against Dalits, who lie at the bottom of India's deeply entrenched social hierarchy system.

Police said they took action after studying the video, taken by another boy and uploaded, which shows the Dalit being punched, kicked and slapped at a government-run school in the eastern state of Bihar.

‘He was being tortured for quite some time,’ Babban Baitha, the investigating police officer, told AFP by phone from Muzaffarpur district.

‘We went through the video which was recorded at the behest of the attackers themselves, and sent them to remand,’ Baitha said, pending the conclusion of his investigation.

Dalits, formerly known as ‘untouchables’, were historically denied a school education and instead performed dirty and menial jobs from a young age.

‘You see, I am a Dalit and so doing well in the examinations or academics, which brings me praise at home, earns me humiliation and abuse in my classroom,’ the boy said in his letter to the NDTV network.

‘You tell me, how should I cope and prepare?’ he said of his final school exams due next year.

The video comes after Dalit protests erupted in July over the public flogging of a group of Dalits wrongly accused of killing a cow -- beasts which are considered sacred in India.

A video of that incident in the western state of Gujarat also went viral and prompted enraged Dalits to call for an end to outlawed but still practised caste discrimination.

Prime Minister Narendra Modi on Tuesday repeated his call for a halt to attacks on Dalits, saying at a public rally that ‘my head hangs in shame’ every time he hears of one.