India will invest US$3 billion (¤2.3 billion) in developing oil and gas fields in Russia to build a partnership in the energy sector, a news report said Sunday. An agreement is likely to be signed during Russian President Vladmiir Putin's Dec. 3-4 visit to the Indian capital, New Delhi, The Hindu newspaper reported. India plans to invest US$1.5 billion (¤1.16 billion) in the Sakhalin-3 gas field and another US$1.5 billion in the joint Russian-Kazakh Kurmangazy oil field in the Caspian sea, which has a potential of up to 1 billion metric tons of oil, the newspaper said. India's Petroleum Minister Mani Shankar Aiyer recently visited Russia to boost energy cooperation between the two countries. "In the first half century of Indian independence, Russia guaranteed our territorial integrity. And in the second half, it may be able to guarantee our energy security," the daily quoted Aiyer as saying. India and Russia have long had close relations. New Delhi sided with the former Soviet Union during the Cold War, and is one of the biggest buyers of Russian arms. India's state-run ONGC Videsh Ltd. already has invested US$ 1.7 billion (¤1.31 billion) in Sakhalin-1 oil fields.