• Raid on Indian base near de facto border with Pakistan
• One of most deadly attacks in insurgency
• Attackers will not go unpunished: Indian PM
• 'Pakistan is a terrorist state': Indian home minister
• Pakistan denies any role

SRINAGAR: India directly accused Pakistan of being behind Sunday's separatist attack on an army base near their disputed frontier that killed 17 soldiers, in one of the most deadly attacks in Kashmir in a quarter-century-old insurgency. Four 'fidayeen' - or commando-style gunmen willing to fight to the death - were confirmed killed after penetrating the base in Uri near the Line of Control with Pakistan, an Indian army spokesman said. Prime Minister Narendra Modi strongly condemned what he called the 'cowardly terror attack'. 'I assure the nation that those behind this despicable attack will not go unpunished,' Modi said in a series of Twitter posts.

We strongly condemn the cowardly terror attack in Uri. I assure the nation that those behind this despicable attack will not go unpunished.

— Narendra Modi (@narendramodi) September 18, 2016 There has been no claim of responsibility. The raid comes amid heightened tension in India's only Muslim-majority region, which has faced more than two months of protests following the July 8 killing of a popular separatist commander whose Hizbul Mujahideen group is based in Pakistan. At least 78 civilians have been killed and thousands injured in street clashes with Indian security forces, who have been criticised by human rights groups for using excessive force. In an even stronger response, Indian Home Minister Rajnath Singh tweeted: 'Pakistan is a terrorist state and should be identified and isolated as such.'

Pakistan is a terrorist state and it should be identified and isolated as such.

— Rajnath Singh (@rajnathsingh) September 18, 2016

There are definite and conclusive indications that the perpetrators of Uri attack were highly trained, heavily armed and specially equipped.

— Rajnath Singh (@rajnathsingh) September 18, 2016

I am deeply disappointed with Pakistan’s continued and direct support to terrorism and terrorist groups.

— Rajnath Singh (@rajnathsingh) September 18, 2016 Pakistan rejected allegations that it was involved. 'India immediately puts blame on Pakistan without doing any investigation. We reject this,' foreign ministry spokesman Nafees Zakaria told Reuters. India and Pakistan have fought two of their three wars since independence over Kashmir. Both claim the former princely state of Jammu and Kashmir in full but rule it only in part. CHOPPERS FLY IN, SMOKE RISES Local television reporters at the scene said the dawn raid had surprised soldiers at the Uri brigade headquarters in their sleep. The attackers torched a building and several tents before the four were killed in a gunfight that lasted several hours. An army spokesman confirmed that the number of soldiers killed in the attack had risen to 17, making the toll far worse than a similar raid on an air force base in Punjab state in January that India blamed on Pakistan-based militants. Reuters television footage showed helicopters flying in to evacuate the injured as an operation continued to secure the area. Smoke rose from the compound, set in mountainous terrain. The Defence Ministry put the number of wounded at 35. Singh, the home minister, chaired a crisis meeting in New Delhi and cancelled trips to Russia and the United States. Defence Minister Manohar Parrikar and the army chief of staff were on their way to Uri to oversee the operation to secure the area and investigate the attack. 'There are definite and conclusive indications that the perpetrators of Uri attack were highly trained, heavily armed and specially equipped,' Singh said in a series of strongly-worded tweets that were confirmed as genuine by his office. U.S. ambassador to India Richard Verma also 'strongly condemned' the Uri attack, which weeks after Secretary of State John Kerry visited New Delhi for strategic talks. After that meeting Kerry urged Pakistan to do more to combat terrorism, while also announcing the resumption of trilateral talks with India and Afghanistan this month in New York, leaving Islamabad looking isolated. WORST BODY COUNT IN YEARS The military death toll was the worst in Indian-ruled Kashmir since a raid in December 2014, also near Uri which is to the west of the region's main city of Srinagar, in which eight soldiers and three police were killed. Before this attack, 102 people had been killed in separatist attacks in India's part of the Himalayan region this year. Among them were 30 security personnel, 71 militants and one civilian, according to a tally by the New Delhi-based South Asia Terrorism Portal. Modi recently raised the stakes in the nuclear-armed neighbours' decades-old feud by expressing support for separatists in Pakistan's resource-rich Baluchistan province. Pakistan has, meanwhile, called on the United Nations and the international community to investigate atrocities it alleges have been committed by Indian security forces in Kashmir. The United Nations is holding its annual general assembly in New York, where Kashmir is likely to come onto the agenda, amid concerns that India's tough rhetoric could herald a military escalation between the South Asian neighbours. Senior Indian journalist and commentator Shekhar Gupta said Pakistan would be 'delusional' to think that India would not respond. 'This India has moved on from old strategic restraint,' he said. Relations between India and Pakistan have been on edge since the New-Year attack on an Indian air force base in Punjab, near the border with Pakistan, that killed seven uniformed men. India has blamed a Pakistan-based militant group for that and a string of other attacks - including one on Mumbai in 2008 that killed 166 people. After initial progress, an attempt to conduct a joint investigation into the airbase attack lost momentum. The two sides have frozen a tentative peace dialogue.

Updated