Senior lawyer and Team Anna member Prashant Bhushan was on Wednesday roughed up by two men in his chambers inside the Supreme Court around 4.15 pm.
The men, who claimed to have links with right-wing group Bhagat Singh Kranti Sena's, barged into Bhushan's chamber and manhandled the senior lawyer.
Later, the men claimed they had attacked the lawyer for his comments on Kashmir. Bhushan had said about two weeks ago in Varanasi that a referendum was possible in J&K.
The police have arrested one of the men, and Bhushan said he would register a First Information Report in connection with the incident.
Former IPS officer Kiran Bedi described the incident as shocking and shameful. " He has been working for the nation. He is a good man. We don't know why they attacked him," she said.
Bhushan was speaking to a TV news channel when two youths barged into his office in the new lawyers chamber opposite Supreme Court on Wednesday afternoon and started showering blows on him.
The lawyer was pulled out of the chair, slapped, dragged and repeatedly punched. He was pinned down on the floor and kicked on his chest. Bhushan's shirt was torn and his spectacles fell when he was roughed up.
As his staff and others gathered, one of the two attackers managed to escape while another was caught by them and handed over to police.
The youths had entered his office claiming that they had an appointment with Bhushan, a prominent Team Anna member who is in the forefront of the fight for a strong Lokpal.
After the attack, Bhushan said it appeared that the youths targeted him for his stand on Jammu and Kashmir.
"They were saying that I have made some comments on Kashmir to which they were taking objection. I have said that a referendum should be held in Kashmir," he said.
A case has been registered and one person has been arrested. Prashant Bhushan was taken to Delhi's Ram Manohar Lohia Hospital for treatment.
With inputs from PTI