More than five months after they were detained without charge, dozens of separatist leaders from Indian-administered Kashmir remain imprisoned as the government in New Delhi seeks to marginalize them, according to sources and figures from a rights group.

Authorities in New Delhi see the removal of activists from communities in the Kashmir Valley as a key aspect of the struggle against the armed militant groups and stone-pelting youths who have been fighting Indian rule, according to interviews with 10 people familiar with the situation.

The round-up of nonviolent separatists, who support Indian-administered Kashmir either joining Pakistan or becoming an independent state, is part of an unprecedented crackdown from India's government to neuter a movement it believes fuels the armed insurrection, the sources said.