United Nations chief Antonio Guterres yesterday called on India and Pakistan "to refrain from taking steps that could affect the status of Jammu and Kashmir." "The Secretary-General has been following the situation in Jammu and Kashmir with concern and makes an appeal for maximum restraint," his spokesperson said.

Indian government stripped the disputed region of its autonomy earlier this week in a move that sent shock waves through South Asia and has seen the restive area come under military lockdown.

Internet and telephone connections in Kashmir have been cut since Monday and a curfew imposed as the authorities feared trouble when the decision was announced.

"The Secretary-General is also concerned over reports of restrictions on the Indian-side of Kashmir, which could exacerbate the human rights situation in the region," Guterres's spokesperson added.

More than 500 people have been rounded up in the latest crackdown in Indian Kashmir which has been on the edge since the right-wing government revoked its autonomy, reports said yesterday.

University professors, business leaders and activists were among the 560 people taken to makeshift detention centres -- some during midnight raids -- in the cities of Srinagar, Baramulla and Gurez, the Press Trust of India and the Indian Express reported.

The detentions came as Prime Minister Narendra Modi was set to address the nation on the radio later yesterday to explain his Hindu nationalist government's decision to revoke the seven-decade long special status of the region through a presidential decree.

Parliament also passed legislation dividing the disputed region -- which has experienced an armed rebellion against Indian rule since 1989 -- into two territories to be governed directly by New Delhi.

Tens of thousands of Indian troops have enforced a strict curfew, which includes no internet or phone services, and are allowing only limited movement on streets usually bustling with tourists flocking to the picturesque valley.

Experts warn that the valley is likely to erupt in anger at the government's shock unilateral move once the restrictions are lifted, which could come as soon as the Muslim festival of Eid on Monday.

Late Wednesday India's aviation security agency advised airports across the country to step up security as "civil security has emerged as a soft target for terrorist attacks" on the back of the Kashmir move.

The developments in Kashmir have irked India's nuclear-armed neighbour Pakistan which Wednesday said it was downgrading diplomatic ties with Delhi. India has yet to respond to Islamabad's actions.

Meanwhile, India yesterday dismissed Pakistan's "alarmist" reaction to its decision to strip Kashmir of its autonomy, and warned its nuclear-armed rival against interfering in what it insisted was a purely internal matter.

India revoked Kashmir's special status in the constitution on Monday and brought it under its direct rule, escalating tensions with Pakistan which has a competing claim to the Muslim-majority region.

Pakistan responded by downgrading its diplomatic ties with India Wednesday, announcing that it would expel the Indian envoy and suspend trade as the row between the neighbours deepened.

The countries have fought two wars over Kashmir.

In a statement the foreign ministry said its decision was "entirely the internal affair of India".

"Seeking to interfere in that jurisdiction by invoking an alarmist vision of the region will never succeed."

New Delhi added that the move would boost economic development in the Himalayan region.

"The government of India regrets the steps announced by Pakistan... and would urge that country to review them so that normal channels for diplomatic communications are preserved," the statement added. The diplomatic spat came as a petition was filed with the Supreme Court by an activist challenging the curfew in Kashmir, which was imposed to suppress any unrest in response to the loss of autonomy.

Activist Tahseen Poonawala and lawyer M.L. Sharma asked the Supreme Court to lift the lockdown and release people who have been detained as part of the crackdown.

Pakistani Nobel laureate Malala Yousafzai, who was shot in the head by the Taliban in 2012, yesterday tweeted that she was "worried about the safety of the Kashmiri children and women, the most vulnerable to violence and the most likely to suffer losses in conflict".

ANI news agency reported that the leader of the opposition in the upper house, Ghulam Nabi Azad from the Congress party, was stopped at Srinagar airport when he flew to the city and sent back.

Experts warn that the valley is likely to erupt in anger at the government’s shock unilateral move once the restrictions are lifted, which could come on the Muslim festival of Eid on Monday.

India’s decision revoking Article 370 drew a swift reaction from Pakistan’s prime minister, Imran Khan who said the move was in breach of international law.

Pakistan has also announced plans to expel India’s top diplomat and suspend trade relations with its neighbour, deepening the row between the countries over Kashmir.

Meanwhile, Pakistan will not resort to military action in a row with nuclear arch-rival India over Kashmir, its foreign minister said yesterday, as tensions soared over New Delhi’s decision to tighten its grip on the disputed region.

The statement from Pakistani foreign minister Shah Mehmood Qureshi eased fears of an all-out clash between the South Asian neighbours, who have already fought two of their three wars over the Himalayan region — but none since they both gained nuclear weapons.

On Monday Delhi stripped the Indian-held portion of Kashmir of its special autonomy, bringing it under its direct rule and deepening animosity with Pakistan, igniting days of debate over how the country should respond.

“Pakistan is not looking at the military option. We are rather looking at political, diplomatic, and legal options to deal with the prevailing situation,” said Pakistani foreign minister Shah Mehmood Qureshi during a press conference in Islamabad.

Tensions remained high, however, with Qureshi’s comments coming on the heels of a decision by Islamabad to downgrade its diplomatic ties with India, suspend bilateral trade, and expel the country’s envoy.