SINGAPORE- Iran has set the official selling price (OSP) of its Light crude oil for Asian buyers at $1.20 a barrel above Oman/Dubai quotes for April, 60 cents lower than the previous month, an industry source with direct knowledge of the matter said on Thursday.

The National Iranian Oil Company also cut prices for three other grades it sells to Asia, setting Iranian Heavy and Forozan at their widest ever discounts against rival grade Arab Medium from Saudi Arabia as Tehran steps up efforts to retain market share in Asia.

The April OSP for Iranian Heavy puts the grade at 70 cents a barrel below Saudi's Arab Medium versus a 55 cent discount in March, Reuters calculation and trade data showed. Forozan's discount to the same Saudi grade was at 41 cents, down from 25 cents in the previous month.

The April OSP for Iranian Light was just 10 cents above Arab Light, the narrowest premium since 2012.

Iran's price cuts are attracting demand from big buyers China and India.

A jump in purchases by top Iranian crude oil buyer China pushed up Asia's overall oil imports from the OPEC producer to a three-month high in January.

Iran has also offered to raise the freight discount on oil sales to India in return for New Delhi agreeing to boost imports.

(Reporting by Florence Tan; Editing by Christian Schmollinger and Subhranshu Sahu) ((Florence.Tan@thomsonreuters.com; +65 6870 3497; Reuters Messaging: florence.tan.thomsonreuters.com@reuters.net))