The purchases come after Washington announced earlier this month sweeping sanctions targeting Russian producers and tankers, disrupting shipments from the world's No. 2 producer.
IOC bought in the latest tender 2 million barrels of Nigerian Okwuibome crude from Vitol and 1 million barrels each of Nigerian Akpo and Angolan Mostarda grades from Shell, the sources said.
The refiner also purchased 2 million barrels of U.S. West Texas Intermediate (WTI) Midland crude from Equinor, they added.
Just a week earlier, IOC bought 7 million barrels of spot Middle Eastern and African crude oil via tenders, including a rare purchase of Abu Dhabi's Murban.
Separately, another refiner Mangalore Refinery and Petrochemical Ltd (MRPL) (MRPL.NS) which issued its first crude import tender in more than a year, did not award the tender, traders said.
