NEW DELHI — An activist from the Indian-controlled portion of Kashmir said on Thursday that he had been prevented from boarding a flight in Delhi as he was on his way to Geneva to speak at a session of the United Nations Human Rights Council.

The activist, Khurram Parvez, of the Jammu Kashmir Coalition of Civil Society, planned to submit a “civil society stakeholder’s report” to the council on the situation in Kashmir, where the death of a commander for a separatist group in July has set off clashes between stone-throwing protesters and Indian security forces. He had also planned to attend a European Union session in Brussels.

More than 70 people, most of them civilians, have been killed in the confrontations, and thousands of civilians and security forces have been injured.