Russia's largest oil producer Rosneft said on Tuesday it has completed the deal to sell a 15 percent stake in Vankor oilfield in East Siberia to ONGC for $1.27 billion.
The deal was initially signed in September 2015.
Vankor, launched in 2009, produces around 440,000 barrels of oil per day. The field is a source of Russian oil supply to China.
In March, ONGC also signed an initial deal to raise its stake in Vankor to 26 percent from 15 percent.