At least 44 Indian paramilitary soldiers were killed on Thursday in occupied Kashmir in the deadliest attack on security forces since 2002, police said.

According to The Hindu, however, paramilitary officials in Srinagar have officially confirmed only 37 deaths so far.

The attack, surpassing one in 2016 when 19 soldiers died, 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 explosion around 20 kilometres from the main city of Srinagar on the main highway towards Jammu.

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 told AFP.

In-Depth: The pursuit of Kashmir

Photos showed the blackened, mangled remains of at least one vehicle littered across the highway.

Unconfirmed photos showed the charred remains of at least one vehicle littered across the highway as black smoke billowed upwards.

Reports said that there were 350 kilos of explosives used.

Meanwhile, The Hindu reported the toll as 40 soldiers killed and four injured.

The blast took place in the Lethpora area of south Kashmir's Pulwama on Thursday afternoon and Jaish-e-Mohammad (JeM) has claimed responsibility, saying it was a suicide attack, according to the publication.

"A convoy in which the soldiers were travelling was attacked by a JeM suicide bomber, who rammed his explosives-laden vehicle into one of the convoy’s buses," reported The Hindu.

According to The Hindu, he was identified as Adil Ahmad Dar alias ‘Waqas Commando’, a resident of Pulwama’s Kakapora.

Officials told NDTV that an unusually high number of personnel were on the move at the same time because the Srinagar-Jammu highway had been shut for the past two days because of bad weather.

The convoy reportedly left Jammu at about 3:30am on Thursday morning. The alleged suicide attacker, driving toward the convoy from the opposite direction, rammed a bus carrying the personnel.

Bullet marks on the bus indicated that more men might have been hiding and might have fired at the convoy, NDTV said.

“It’s a terror incident; we are looking into what caused it. We suspect it was a vehicle-bound attack,” a top CRPF officer told reporters.

Asked how the attackers could carry out the attack on such a heavily-guarded highway, the CRPF said: “It is a matter of investigation.”

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.

Calling the attack “despicable and dastardly”, Prime Minister Narendra Modi said: “The sacrifices of our brave security personnel shall not go in vain.”

He tweeted: “The entire nation stands shoulder to shoulder with the families of the brave martyrs. May the injured recover quickly.”

Pakistan expresses concern

Pakistan termed the attack a matter of grave concern, adds APP.

The Foreign Office spokesperson in a statement issued in Islamabad strongly rejected any insinuation that sought to link the attack to Pakistan without investigations.

“We have always condemned acts of violence anywhere in the world,” the FO spokesperson said.

“We strongly reject any insinuation by elements in the Indian media and government that seek to link the attack to Pakistan without investigations,” the spokesperson remarked.

India has an estimated 500,000 soldiers in Kashmir, which has been divided between India and Pakistan and riven by unrest since the end of British rule in 1947.

Kashmiris have been fighting for an independent Kashmir, or a merger with Pakistan, since 1989.

New Delhi accuses Pakistan of fuelling the uprising that has left tens of thousands of civilians dead. Islamabad denies the charge, saying it only provides diplomatic support to Kashmiris' right to self-determination.