Indian security forces have arrested more than 500 people since New Delhi imposed a communications blackout and security clampdown in divided Kashmir, where people remained holed up in their homes for a fourth day.
Pakistan, which claims the divided Himalayan region together with India, on Thursday suspended a key train service with India over a change in Kashmir's special status by New Delhi, as tensions between the rivals soared.
India's government this week revoked the special status of Jammu and Kashmir and downgraded the region from statehood to a territory. Rebels in Muslim-majority Kashmir have been fighting Indian rule in the portion it administers for decades.
State-run All India Radio said cross-border firing by Indian and Pakistani troops hit the Rajouri sector of Indian-controlled Kashmir late on Wednesday.
Indian prime minister Narendra Modi said the downgrading of Indian-administered Kashmir from a state to a federally controlled territory will help end decades of terrorism and separatism incited by Pakistan. In a nationally broadcast speech, he described the changes as historic and assured residents the situation would soon become normal.
Mr Modi said local elections would soon be held in Jammu and Kashmir and the people would be able to “choose their leaders, their CMs [chief ministers] like they have done before.”
Pakistan's foreign minister said Islamabad was not considering any military actions and instead was looking at political and legal options to challenge India's changes.
Activist Ali Mohammed told New Delhi Television that he had been organising ambulances to carry sick poor people to hospitals in Srinagar, the main city in India's portion of Kashmir, as local residents could not even use phones to ask for medical help.
In New Delhi, opposition Congress party activist Tehseen Poonawalla said he expected the Supreme Court to hear his petition on Thursday seeking the immediate lifting of a curfew and other restrictions, including blocking of phone lines, internet and news channels in Kashmir.
He also sought the immediate release of Kashmiri leaders who have been detained, including Omar Abdullah and Mehbooba Mufti.
In response to India's action, Pakistan's railways minister Sheikh Rashid Ahmad suspended the Express, or Friendship Express, train service to India. The suspension announcement was made as passengers were waiting to board a train in the eastern city of Lahore to travel across the border.
Islamabad on Wednesday said it would downgrade its diplomatic ties with New Delhi, expel the Indian ambassador and suspend trade.
Prime minister Imran Khan told Pakistan's National Security Committee that his government would use all diplomatic channels "to expose the brutal Indian racist regime" and human rights violations in Kashmir, the government's statement said.
India hit back, saying in a statement that “the intention behind these measures is obviously to present an alarming picture to the world of our bilateral ties”.
Pakistan's foreign ministry spokesman Mohammad Faisal said authorities were considering approaching the International Court of Justice for a case against India for downgrading Kashmir's special status.
He condemned the communications blackout and security clampdown, saying: “Kashmir has been converted into the world’s biggest jail.”
“They are taking such actions in a panic,” he said, adding India has “touched something they don’t know how to get out of it”.
India and Pakistan have fought two of their three wars over control of Kashmir. The first ended in 1948 with a UN-brokered ceasefire that left Kashmir divided and promised its people a UN-sponsored referendum on the region’s future. – AP/Reuters