It will thus become the second Indian company to have a refinery abroad.
The Ruias-promoted Essar Energy owns the Stanlow refinery in the UK and has 50 per cent interest in Kenya Petroleum Refinery.
IOC operates 10 refineries in India and the capacity of its Sri Lankan refinery is expected to be 5-9 mtpa (million tonnes per annum).
"We have done the analysis and have first-hand information on the kind of refinery we plan to set up in Sri Lanka. We are in discussions with the Sri Lankan government for tax concessions, a holiday for customs and excise, and other benefits that a refinery should accrue to us.
The land will come from the Sri Lankan government," said a senior IOC official who did not wish to be named.
IOC is already present in Sri Lanka through its subsidiary Lanka IOC.
That company is the only private oil company that operates retail fuel stations in Sri Lanka.
The state-owned Ceylon Petroleum Corporation also operates such stations.
Lanka IOC has 157 fuel retail outlets. IOC's refinery, the official added, could come up adjacent to an existing refinery in Sapugaskanda commissioned 43 years ago and processing 5,200 million tonnes per day of Iranian light crude oil.
IOC plans to set up the refinery
Bowling at the death a concern for Gambhir
High excise duty dampens branded fuel market
Crude down, yet oil cos refuse to cut prices
Stats: Raina is 10th Indian bat to score 1000 runs vs SL
Photos: India sneak past Lanka in 3rd ODI