The PM’s unusually strong remarks invited a sharp reaction from Pakistan, which said the statement would “not only ratchet up tensions but also occlude facts and destroy all prospects of serious and objective investigations into the Mumbai attacks”.

Pakistan also rejected the material handed over to it by New Delhi on Monday in support of its claims that the terrorists in Mumbai had come and were handled from Pakistan. Islamabad said the material did not comprise “credible evidence”.

Singh made repeated references to Pakistan in his inauguration speech at the Chief Ministers’ conference, and dismissed the Pakistani line that ‘non-state actors’ might have been responsible.

“The terrorist attack in Mumbai in November last year was clearly carried out by a Pakistan-based outfit, the Lashkar-e-Toiba,” the PM said. “On the basis of the investigations carried out, including (those by) the agencies of some foreign countries whose nationals were killed in the attack, there is enough evidence to show that, given the sophistication and military precision of the attack, it must have had the support of some official agencies in Pakistan.”

Home Minister P Chidambaram had made a similar statement over the weekend, saying an operation like the one in Mumbai could not have been carried out without the complicity of “state actors or state-assisted actors”.

The PM went on to describe Pakistan’s government as “fragile” and “irresponsible”, and accused it of creating “war hysteria”.

“Our problems are compounded by the fact that we have a highly unpredictable and uncertain security environment in our immediate neighbourhood. The governments in some of our neighbouring countries are very fragile in nature. The more fragile a government, the more it tends to act in an irresponsible fashion. Pakistan’s responses to our various demarches on terrorist attacks is an obvious example,” he said.

Then, distinguishing between Pakistan-backed terror and other internal security threats to India such as left-wing extremism and insurgency in the North-east, the PM said, “Terrorism, on the other hand, is largely sponsored from outside our country, mainly Pakistan, which has utilized terrorism as an instrument of state policy”.

In response, the Pakistani Foreign Ministry warned that India’s approach was “fraught with grave risks” and would “further vitiate the situation in South Asia”. The statement repeated Pakistan’s well-known line: “Pakistan has suffered more terror attacks than India. But we have not lost our equanimity”.

It stressed that Pakistan was not a state sponsor of terrorism, and advised India “to demonstrate restraint and responsibility”.

“Vilifying Pakistan or for that matter any of its state institutions is unwarranted and unacceptable. This is a sure way to close avenues of cooperation in combating this menace,” the statement said.

Singh, however, went on to make another reference to cross-border terrorism in the evening, though this time he did not name Pakistan.

“On our part, we will spare no effort to deal with terrorist and insurgent groups operating from neighbouring countries. We are determined to put an end to terrorism sponsored from across the border with all the means at our command,” he said in his concluding speech at the Chief Ministers’ conference. He urged Chief Ministers to make every effort to ensure zero-tolerance towards terrorism.