South Korea's Samsung Total Petrochemicals Co has revived a contract to buy Iranian oil after a year's hiatus, as thin margins in plastics make the cheap fuel from Iran hard to resist, Reuters reported citing people familiar with the deal.

Stringent U.S. and European sanctions aimed at reducing Iran's oil income and forcing Tehran to curb its nuclear program have made shipping and paying for the oil hard, halving the Islamic Republic's crude exports.

The deal is a rare example of a buyer returning to the market for Iranian oil despite the obstacles arising from sanctions and efforts by Western powers to stem the flow.

After jarring interruptions in exports from Iran last year that included a halt in shipments to top consumers Japan and South Korea, importers have found ways to keep oil flowing without violating sanctions.