Crude oil throughput last month stood at 5.27 million barrels per day (21.58 million tonnes), the data showed.
"Refiners are buying cheap Russian oil as far as it is possible and then exporting high-priced diesel especially to Europe, where diesel prices have risen to astronomically high levels," said Ehsan Ul Haq, an analyst from Refinitiv.
Diesel supply has become a global concern since sanctions against Russia reshaped fuel trade and sent international inventories to historic lows.
Data last week showed India's April crude oil imports were the highest in 3-1/2 years mainly on the back of higher Russian flows to the world's third larger importer and consumer of oil.[O/INDIA2]
India's purchase of Russian oil has surged ever since the invasion of Ukraine, at a time when Western sanctions have prompted many oil importers to shun trade with Moscow.
"Refiners are boosting their runs in order to profit from exceptionally strong margins... The refining business is a cyclical business and refiners have to take profits as long as high margins last," Haq added.
Indian refiners operated at an average rate of 104.51% capacity, the government data showed. Refineries can operate at more than their usual capacity through technical alterations.
Top refiner Indian Oil Corp (IOC) last month operated its directly-owned plants at 108.32% capacity. Reliance, owner of the world's biggest refining complex, operated its plants at 91.90% capacity in April.
However, crude oil production fell nearly 1% to about 603,000 barrels per day (2.47 million tonnes), the data showed. Natural gas output rose 6.6% year on year to 2.83 billion cubic metres, the release added.
(Reporting by Ashitha Shivaprasad in Bengaluru, additional reporting by Swati Verma; Editing by Krishna Chandra Eluri)
By Ashitha Shivaprasad
