NEW DELHI  - Indian Prime Minister Manmohan Singh used his Independence Day speech on Friday to warn Pakistan to rein in terrorism, as peace talks between the two countries falter 61 years after they were divided. Singh said a suicide bombing last month against the Indian embassy in Kabul had "cast a shadow over our efforts to normalise ties with Pakistan." New Delhi has blamed the bombing, which killed scores of people including two Indian diplomats, on Pakistan's intelligence agency, the ISI. Standing behind bulletproof glass at New Delhi's ancient Red Fort, Singh said he had personally conveyed his "concern and disappointment to the government of Pakistan." "If this issue of terrorism is not addressed, all good intentions that we have for our two peoples to live in peace and harmony will be negated," he said. India and Pakistan restarted peace talks in January 2004 but Indian officials have said the dialogue is under strain after the embassy attack. Pakistan denies it was involved.India also accuses Pakistan of supporting an insurgency in Kashmir, the trigger for two of the three wars between the nations since they gained independence in 1947. New Delhi, which suspects Islamabad of links to many of the bomb blasts that regularly strike Indian cities, was on high alert during the day's celebrations. Police said the tight security was prompted by undefined information about a possible attack. "We have intelligence inputs about extremist groups planning to target prominent leaders and symbols of national importance," Joint Police Commissioner SN Srivastava told a news conference late Thursday. Elite commandos were called out to join 17,000 paramilitary soldiers and New Delhi's 70,000-strong police department. Security was also high in Kashmir, which has been engulfed in deadly protests over a land dispute that has inflamed religious tensions and stoked a long-standing separatist campaign. Touching on the Kashmir violence, Singh used his speech to attack those intent on "dividing people in the name of religion" - an apparent reference to both Hindu and Muslim hardliners. In Mumbai, thousands of police searched the city as a precaution against copycat attacks after serial blasts rocked Ahmedabad and Bangalore last month. At least 50 people were killed and 170 others injured in the bombs, which Singh said in his address demonstrated that "terrorism, extremism, communalism and fundamentalism" threatened the future of India.