SINGAPORE/NEW DELHI : Indian Oil Corp, the country's largest state refiner, has bought nearly 20 million barrels of spot crude from West Africa and the Middle East for delivery in early 2021, three trade sources said on Monday.The purchase is the largest by the refiner since the COVID-19 pandemic broke out in the world's third largest crude oil importer in second quarter.IOC's chairman said this month that the refinery has been operating at 100% capacity since early November as local fuel demand has recovered.IOC purchased the cargoes over three rounds of tenders this month for deliveries in January and February, the sources said.Low-sulphur crude from Nigeria and Angola made up the bulk of the supplies, the sources said, while IOC also.