Security forces enforce an indefinite curfew ahead of a separatist rally.
Mirwaiz Umar Farooq, the chairman of Kashmir’s main separatist alliance, and Syed Ali Shah Geelani, the member of the All Parties Hurriyat Conference, were earlier detained in overnight raids in Srinigar, police said.
Dozens of people have been killed in several weeks of protests sparked by a move by the Indian government to give land to a Hindu shrine.
A statement from the All Parties Hurriyat Conference said: “The people of Kashmir were ready to defy the curfew and carry out the march to protest against Indian occupation.”
Police have killed at least 24 Muslim protesters and more than 500 have been injured in clashes in two weeks of demonstrations held in the Kashmir Valley.
The crisis has strained relations between India and Pakistan.
It has also raised fears of communal tension in the state, split between the Hindu-majority Jammu region and the Muslim Kashmir Valley.
A dispute over land for Hindu pilgrims visiting a shrine in Kashmir led to the rallies this month, boosting separatists who want India’s only Muslim-majority region to secede.
With a general election approaching early next year, analysts say there is little chance of Manmohan Singh, the Indian prime minister, giving any concessions to the protesters.
In Kashmir, more than 43,000 people have been killed in unrest involving Indian troops and separatists since 1989.
Human rights groups say at least 60,000 are either dead or missing.
Levels of violence in Kashmir have fallen in the past few years amid tighter Indian security and a tentative peace process between Pakistan and India.