Neighbours China and Pakistan, which both claim parts of the region, have voiced fierce opposition to India scrapping a constitutional provision that had allowed the country's only Muslim-majority state to make its own laws.
Pakistan said on Wednesday it will "downgrade" diplomatic relations and suspend bilateral trade with archrival India after New Delhi stripped its portion of the contested Kashmir region of autonomy conferred onto it at the time of ascension.
A spokesman for India's Foreign Ministry did not immediately respond to a request for comment.
The Hindu nationalist Indian government passed a presidential decree on Monday to strip the Muslim-majority Kashmir region of its longstanding semi-autonomous status, seeking to tighten control over the region.
Rahul Radhakrishnan has more.
At least one protester died in a police chase during the curfew in India-administered Kashmir's main city, a police official told AFP on Wednesday. The conditions leading to the death could not be verified due to a communication blackout in India-administered Kashmir.
Neha Poonia has more.
Changing Kashmir's demographics
The scrapped constitutional provision was a formalisation of the then independent princely state's 1947 accession treaty with India.
The law, Article 370 of the Constitution, forbids Indians outside the state from permanently settling, buying land, holding local government jobs and securing education scholarships.
Critics of such a measure say that in doing away with Article 370, New Delhi hopes to change India-administered Kashmir's Muslim-majority demographics by allowing in a flood of new Hindu residents.
Despite a paralysing curfew, imposed to head off unrest, sporadic protests have been reported by residents in the main city, Srinagar.
A police official, speaking on condition of anonymity, claimed that in one incident a youth being chased by police "jumped into the Jhelum River and died."
The incident happened in Srinagar's old town, which has become a hotbed of anti-India protests during the three-decade-long insurgency in Kashmir that has left tens of thousands dead.
At least six people have been admitted to the hospital in Srinagar with gunshot wounds and other injuries during protests.
Indian police insist that the valley has been mainly peaceful since the curfew was imposed at midnight on Sunday.
Authorities had placed large parts of the disputed region under lockdown amid a massive troop build-up by India, which traded accusations of clashes with Pakistan at the de facto border.
The recent tensions started in the last 10 days after New Delhi deployed at least 10,000 troops, but a security source told AFP news agency a further 70,000 had been dispatched in what is believed to be an unprecedented level.
India maintains a deployment of 500,000 heavily-armed troops in the tiny Himalayan region, which has been divided between the South Asian nation and Pakistan since their split in 1947.
Two months after India won independence from British rule in August 1947, Maharaja Hari Singh, the then-ruler of Jammu and Kashmir, signed a Treaty of Accession for the state to join the rest of the union, formalised in Article 370 of the Indian constitution.
Then governor-general and last viceroy Lord Mountbatten backed his decision with an understanding that this would only be temporary accession prior to "a referendum or a plebiscite."
Under the accession terms, India's jurisdiction was to extend to Kashmir's external affairs, defence and communications.
Resistance groups demand that Kashmir be united either under Pakistani rule or as an independent country in a UN-backed or sponsored plebiscite.
Anti-India sentiment runs deep in Kashmir's mostly Muslim population and most people support the rebels' cause against Indian rule.
Nearly 100,000 people have been killed in the armed rebellion and civil uprising and the ensuing Indian military crackdown since 1989.