The companies have signed a non-binding term sheet for Rosneft to buy an equity stake of up to 49 percent in Essar Oil, the Indian company said in a statement on Thursday. Rosneft, the world's top listed oil producer, has long sought to increase its exposure to the global markets but its efforts have been hampered by Western sanctions over Moscow's role in the Ukraine crisis. The deal with Essar from India, a country Russia has close ties with since the Soviet era, was announced as Indian Prime Minister Narendra Modi met President Vladimir Putin on the fringes of a summit of emerging nations.