India's state-run Mangalore Refinery and Petrochemicals Ltd has bought 1 million barrels of Russian Urals crude for May loading via a tender, three trade sources familiar with the deal said, a rare purchase driven by the discount offered.

Refiners in India, the world's third biggest oil importer and consumer, have been snapping up Russian oil through spot tenders since Russia's invasion of Ukraine on Feb. 24, taking advantage of deep discounts as other buyers back away.

One of the sources said a European trader had sold the cargo. The price agreed for the deal was not immediately clear.

MRPL did not respond to a Reuters request for comment.

With MRPL's purchase, India has so far booked at least 14 million barrels of Russian oil since Feb. 24, compared with nearly 16 million barrels in all of 2021, according to Reuters calculations.

The Urals oil discount to dated Brent has hit a record for the post-Soviet era as buyers stayed away from Russian oil . Unlike several Western countries, India has not banned Russian oil imports.

"We have started buying (Russian oil). We have received... quite a number of barrels, I would think about 3-4 days' supplies, and this will continue," Finance Minister Nirmala Sitharaman said last week.

"India's overall interest is what is kept in mind... I would put my country's national interest first, and I would keep my country's energy security first," she said, adding that if oil is available at a discount, "why shouldn't I buy it?".

The United States has said it will not set any "red line" for India on its energy imports from Russia, but does not want to see a "rapid acceleration" in purchases.