KOLKATA: Former Army chief General Shankar Roychowdhury (Retd) on Friday said the Pahalgam terror attack was due to "intelligence failure" and demanded accountability at the highest levels.

Speaking to PTI, Roychowdhury, the country's 18th Army chief, said, "I suspect intelligence failure. Somebody must answer for the lapses. There is definitely someone responsible for negligence and they must be held accountable for the consequences."

He also said Pakistan and its intelligence agency ISI (Inter-Services Intelligence) have a role behind the Pahalgam attack, where 26 civilians, mostly tourists were shot dead by terrorists in front of their family members.

"There must be complacency somewhere. How did so many infiltrators manage to get through? This needs to be investigated," he added.

The Lashkar-e-Taiba (LeT) proxy group, The Resistance Front (TRF), has claimed responsibility for the attack.

Asked whether the Indian government's diplomatic sanctions on Pakistan were an adequate response, Roychowdhury said, "The diplomatic steps taken are not enough. Resistance measures will have to be taken. What shape they take depends on us. Conventional measures would not be enough."

"We will have to react in kind, that is the only way I see it. We must retaliate by maintaining international diplomacy. Enough is enough," Roychowdhury said.

On the possibility of an insider assisting the attackers, he said, "I am not suggesting that directly, but we must keep our eyes and ears open. Pakistan and the ISI have always played an active role. We have our own intelligence agency, RAW, and we must utilise it effectively."

On whether Pakistan Army chief General Asim Munir's statement on Kashmir acted as a catalyst for the terrorists, Roychowdhury said, "I think that is the only thing that works in Pakistan. Definitely, that worked as an impetus for terror outfits. I must say attacking civilians must not be done."

General Munir in a recent address had described Kashmir as Pakistan's "jugular vein".