SRINAGAR — At least 37 Indian paramilitary soldiers were killed on Thursday in Indian-administered Kashmir in one the deadliest attacks on government forces there, police said.

The suicide bombing outside Srinagar is claimed by an Islamist group.

"The sacrifices of our brave security personnel shall not go in vain," Indian Prime Minister Prime Minister Narendra Modi tweeted, calling the attack "despicable".

The attack saw explosives packed inside a van rip through buses in a convoy of 78 vehicles carrying some 2,500 members of the paramilitary Central Reserve Police Force (CRPF).

Two blue buses carrying around 35 people each bore the brunt of the massive blast, heard miles away, around 20km from the city of Srinagar on the main highway to Jammu.

The Press Trust of India (PTI) news agency reported that at least 39 people were dead, while other press reports said the number could exceed 40. 

Some of the bodies were so badly blown up that officials feel it may take some time to identity them, PTI reported. The convoy was bringing the troopers back from leave to rejoin active service.

It was unclear whether the van containing the explosives was driven into the convoy or whether it was detonated when the buses were adjacent.

"It was a powerful explosion. The explosive was car-borne," CRPF spokesman Sanjay Kumar said.

Reports said that there were 350 kilos (770 pounds) of explosives used.

Local media reports said the Pakistan-based Jaish-e-Mohammed Islamist group claimed responsibility.

A spokesman for the group told a local news agency that the "suicide attack" was carried out by Aadil Ahmad, alias Waqas Commando, a known militant from the area.

After the attack, hundreds of government forces cordoned around 15 villages in the district the bomber came from and started searching house-to-house, a police officer and witnesses said.

Not in vain

The US condemned the attack in "the strongest terms" on Thursday, and called on "all countries...to deny safe haven and support for terrorists."

State Department deputy spokesman Robert Palladino said Washington was "resolutely committed to working with the Indian government to combat terrorism in all its forms".

The attack surpasses one in 2016 that was the biggest in 14 years, claiming the lives of 19 soldiers in a brazen pre-dawn raid by militants on the Uri army camp.

India blamed militants in Pakistan for that attack, and responded with strikes across the heavily-militarised Line of Control, the de-facto border dividing the nations.

India’s foreign ministry, in a statement late Thursday, blamed Pakistan.

"This heinous and despicable act has been perpetrated by Jaish-e-Mohammed, a Pakistan-based and supported terrorist organisation proscribed by the United Nations and other countries," the foreign office said. 

Islamabad, however, rejected the suggestion that it was involved and said it had "always condemned acts of violence."

"We strongly reject any insinuation by elements in the Indian media and government that seek to link the attack to Pakistan without investigations," the Pakistan foreign ministry said. – AFP