That boosted Russia's share in the world's third largest importer and consumer to nearly 41% last month, the data showed.
Meanwhile, supply from Saudi Arabia dropped to a 10-month low, the data showed, after Saudi Aramco hiked term prices for a second month in May.
Refiners in India have been gorging on Russian oil, sold at a discount after some European nations shunned purchases from Moscow over its invasion of Ukraine in February 2022. Also, similar grades from regions mainly in the Middle East are costlier.
India shipped in about 5.1 million bpd oil in May, a growth of about 5.6% from April, the data shows.
India's Russian oil imports in May rose 14.7% from April and 5.9% from a year ago, the data shows.
"Russian oil was available in plenty and at better discounts last month due to lower demand from China," said an official at one of the Indian refineries.
Indian private refiners Reliance Industries (RELI.NS), opens new tab and Nayara Energy, majority owned by Russian entities, have signed a term deal to buy Russian oil.
In contrast, state-refinersIndian Oil Corp (IOC.NS), opens new tab, Bharat Petroleum Corp (BPCL.NS), opens new tab, Hindustan Petroleum (HPCL.NS), opens new tab and Mangalore Refinery and Petrochemicals (MRPL.NS), opens new tab are buying Russian oil from the spot markets.
Russia continued to be the top oil supplier to India, followed by Iraq and Saudi Arabia.
Indian refiners shipped in 508,500 bpd Saudi oil in May, down 16.4% from April, and 1 million bpd from Iraq up 22.2% on month, the data showed.
Also, last month Indian refiners received 176,000 bpd oil from the U.S., the data showed.
Higher intake of Russian oil has been denting the share of the Middle Easter oil in India's crude mix and also that of oil producers cartel OPEC, the data showed.