India received about 576,000 barrels per day (bpd) of Iranian oil in August, up about 10 per cent from July, according to trade sources and ship arrival data compiled by Thomson Reuters Supply Chain & Commodities Research.
The August imports from Iran are likely a record although reliable data is available only back to 2001.
Iran used to be India's second biggest oil supplier - a position now held by Iraq - before sanctions aimed at Tehran's nuclear programme began undercutting its petroleum trade.
The sanctions were lifted in January, and in August, Iran's crude exports, excluding condensate, rose to near pre-sanctions levels at 2.11 million bpd, with loadings headed for India surpassing those for China, Tehran's top oil client.
India's oil imports from Iran last month were nearly triple the 199,000 bpd taken in August a year ago, according to the tanker arrival data.
India's Iran oil purchases rose nearly 70 per cent to 451,000 bpd over those five months from about 266,000 bpd in the same period a year ago, the data showed.
India's oil imports from Iran are set to surge to a seven-year high in the year that began April 1, with the nation's state-owned and private refiners together buying at least 400,000 bpd on average.
In the first eight months of 2016, India's oil imports from Tehran rose 84 per cent to about 395,000 bpd, the data showed, in comparison with 214,000 bpd a year ago.
Private refiner, Essar Oil, was the top Indian client of Iran in August, followed by Indian Oil Corp and Mangalore Refinery and Petrochemicals Ltd.