New Delhi: Prime Minister Manmohan Singh Tuesday squarely blamed Pakistan for the Nov 26 terrorist attack in Mumbai, calling the government there "fragile" and "irresponsible" and said it had "utilized" terrorism as an instrument of state policy against India.

"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 example," said Manmohan Singh while addressing a meeting of all the state chief ministers on the issue of internal security.

This is the first time the prime minister has explicitly singled out Pakistan's role in the 26/11 attacks and detailed how it continued to harbour terror groups that were antagonistic to India.

His statement comes close on the heels of Home Minister P. Chidambaram categorically rejecting the Pakistani theory that the people behind the Mumbai attacks were non-state actors.

"Terrorism, on the other hand, is largely sponsored from outside the country, mainly Pakistan, which has utilised terrorism as an instrument of state policy," asserted the prime minister, a day after the government handed over material evidence to Pakistan linking Pakistani based militants to the Mumbai attacks.

Pointing out that terrorists were enlarging the canvas of threats concentrating on attacking economic, infrastructure, and iconic targets, Manmohan Singh urged greater vigilance along the 7,500 km coast line and better monitoring of maritime activity in territorial waters.

He also called for a strong sense of nationhood to withstand both types of threats.

"Our nation is clearly united in our determination to defeat both external as well as internal security challenges. Our determination and sense of nationhood derives from our inheritance of a great historical experience of a multi-ethnic, multi-religious, multi-caste and multi-lingual society."

"Today, even as Pakistan engages in whipping up war hysteria, our nation remains steadfastly united and, if anything, the process of national consolidation is becoming stronger."

Though India's external policies have been dictated by a desire to have a supportive neighbourhood, the prime minister lamented that was not possible.

"Unfortunately, we cannot choose our neighbours, and some countries like Pakistan have in the past encouraged and given sanctuary to terrorists and other forces who are antagonistic to India."

"Consequent upon this, those incharge of the terrorist infrastructure in Pakistan have resorted to other stratagems to infiltrate terrorists into India. Infiltration is occurring via Nepal and from Bangladesh, though it has not totally ceased via the Line of Control."

"We are aware that the sea route is another option that is now being exercised. A few interceptions have taken place, though we failed to intercept the 10 Pakistani terrorists who came by sea from Karachi."