The trader won the Sokol cargo at near parity with the Dubai benchmark in a recent tender floated by Russian oil giant Rosneft, the source said. IOC did not respond to Reuters email seeking comment.
Rosneft last month offered six cargoes of Sokol crude for loading in November to early December, signaling that output from the Sakhalin-1 project may be recovering following the departure of former operator Exxon Mobil Corp.
The source said IOC had purchased that cargo at about flat to a minor discount to Dubai on a delivered basis from a trader, one of those that became active in Russian oil after imposition of western sanctions against Moscow following its late-February invasion of Ukraine.
Crude oil tanker Eurodignity started its voyage from Yeosu port in South Korea on Tuesday for arrival at Paradip port on Nov. 23, trade flows data on Refinitiv showed.
The source said IOC did not participate in the Rosneft tender as the Russian company was asking for prepayment.
Normally cargoes of Sokol oil are first shipped from the De-Kastri terminal in Russia's Far East using ice-class vessels to South Korea, where they are then reloaded onto conventional tankers.
(Reporting by Nidhi Verma; Editing by Jan Harvey)
By Nidhi Verma and Florence Tan