New Delhi - Evidence shows that the Mumbai terrorist attacks must have had the support of some official agencies in Pakistan, Indian Prime Minister Manmohan Singh said Tuesday.

"The terrorist attack in Mumbai in November last year was clearly carried out by a Pakistan-based outfit, the Lashkar-e-Taiba," Singh said in his inaugural address at a conference of chief ministers to discuss India's internal security situation.

"On the basis of investigations carried out, including 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," the prime minister said.

Ten gunmen, who Indian agencies claim arrived in Mumbai by a sea route from Pakistan, killed more than 170 people in three days of mayhem beginning November 26.

The incident has escalated tension between nuclear-capable South Asian neighbours India and Pakistan, which have fought three wars since 1947.

India on Monday handed over material to Pakistan, which it claims clearly indicates that the gunmen, including the lone survivor who is in police custody, had direct links with that country.

Singh said terrorism, Maoist rebel groups and insurgency in the north-east were the the most serious threats to India's security and a strong sense of nationhood was important to withstand these threats.

"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," he said.

The insurgencies by the Maoists and North-east rebels were primarily homegrown, Singh said.

Terrorism was, however, largely sponsored from outside India, mainly by Pakistan, which used terrorism as an instrument of state policy, Singh added.

"We must convince the world community that states that use terrorism as an instrument of foreign policy, must be isolated and compelled to abandon such tactics," he said.

Terrorists were increasingly using new technology, skills and state-of-the-art communication and India urgently needed to strengthen its intelligence gathering mechanisms to prevent further attacks, Singh said. (dpa)