* Student union leader ‘attacked on way to court’
* Students protest in campuses across the country
* Government, Delhi police chief defend actions
* Indian public deeply divided over case
Kanhaiya Kumar, head of the student union at Delhi's Jawaharlal Nehru University (JNU), was rushed from a car through a gate into the court by police officers protecting him with a riot shield.
He was later remanded in custody by the court until March 2.
Lawyers chanting nationalist slogans earlier barged into the compound and threw stones at reporters, defying a Supreme Court order banning protests after a punch-up at a hearing on Monday.
Wednesday's remand hearing was briefly adjourned as the Supreme Court rushed a team of commissioners to investigate, after lawyers for Kumar said he had been attacked inside the Patiala House court in New Delhi.
"A person has come dressed as a lawyer and beaten him up inside the court premises today," said defence lawyer Vrinda Grover. "The police couldn't do anything, it's a complete violation of the Supreme Court order."
Kumar told the court he was manhandled on the way in and lost his shoes in the process. "I was rebuked, I was attacked," he said.
Kumar, 28, was arrested at a student rally last week held to commemorate the anniversary of the execution of a Kashmiri separatist for his role in an attack on the Indian parliament in 2001.
Supporters of Kumar, a member of the leftist All India Students' Federation (AISF) that has a Soviet hammer and sickle as its logo, deny he made incendiary remarks.
A smartphone video of a speech given by Kumar during the event has been widely reposted on Indian media. In it, Kumar criticises a right-wing student fraternity and the Rashtriya Swayamsevak Sangh, a Hindu-nationalist umbrella group to which Prime Minister Narendra Modi's ruling party belongs.
He also explicitly eschews violence.
The case has triggered the biggest nationwide protests by students in a quarter of a century and a tough response from supporters of the nationalist government who say the actions against Kumar are justified.
In a climate of growing polarisation, Modi's Bharatiya Janata Party (BJP) is cranking up Hindu-nationalist rhetoric ahead of an election in India's most populous state, Uttar Pradesh, next year.
The opposition Congress party and communist leaders have rallied behind Kumar and his AISF in its standoff with the pro-BJP student union, the Akhil Bharatiya Vidyarthi Parishad (ABVP).
As protests have escalated, the chief of Delhi police faces accusations of taking political orders and failing to investigate alleged violence by nationalists loyal to Modi.
In one case, BJP lawmaker O.P. Sharma attacked a communist politician on the street outside the courthouse on Monday in an incident caught on television.
"If I had committed a crime then my party would have thrown me out," Sharma told Reuters. "I am ready to face any kind of punishment to defend my core philosophy."
Some commentators and legal experts fault the government for exploiting the colonial-era sedition law to silence its opponents, when it should instead have left college rectors to manage what they say is no more than exuberant student debate.
"Any critical comment against government policy does not amount to sedition," Soli Sorabjee, a former attorney general of India, told Reuters. "Only acts that can disturb law and order or incite violence can be stamped as sedition."
Modi's party rejected the criticism.
"The constitution is clear that freedom of speech does not extend to the right to promote secession; slogans that demand the disintegration of India cannot be condoned," said M.J. Akbar, a BJP spokesman.
Particular attention has focused on the role of Delhi police chief B.S. Bassi, who has cracked down on student agitators but not acted against Sharma.
Earlier Bassi emerged confident from a meeting with officials in Modi's office, saying police had "ample evidence" against Kumar. "It was only on the basis of the evidence that we arrested him," he told reporters.
After Kumar's hearing, Bassi added: "We have managed the situation. We ensured that no serious breach of public order occurred despite a very charged environment. The use of force, in my opinion, would have been counterproductive."
Kumar's mother denied accusations of disloyalty.
"My son spoke the truth. He was arrested because his views questioned the government policy and their agenda," Meena Devi told Reuters by telephone from her home in the eastern state of Bihar. "My son can never be a traitor, he would lay down his life for his country."