Indian firm OVL is buying a 15% stake in the massive Siberian oil field in Russia’s far East, Dispatch Times reported.

The deal was finalized over the Vankor field, the second largest in Russia. Up to this point the field had been developed exclusively by Rosneft.

OVL is the overseas investment arm of major state-owned group ONGC. The deal signed for reportedly $1.2b, said The Times of India.

The deal shows a strengthening of ties between India and Russia. Political approval for the purchase was reportedly given at the recent summit for BRICS and SCO held in the Russian city of Ufa recently.

The agreement seems to be another step toward diversifying energy sources for India. The rapidly expanding country has struggled to provide energy for its population. OVL already owns a 20% stake in the Sakhalin-I project, also in Siberia.