India's oil imports from Iran have fallen to their lowest since June 2016, shipping data shows, in possible retaliation for Tehran not awarding a gas field development to Indian companies.

India, Iran's top oil client after China, shipped in 487,600 barrels per day (bpd) in May, about 9 per cent less compared with April and nearly 40 per cent less than a peak registered in October, according to ship tracking data obtained from sources and data compiled by Thomson Reuters Oil Research & Forecasts.

Most Western-led sanctions against Tehran's nuclear programme were lifted in January last year, and India's Iranian crude imports began climbing two months later in March.

In the fiscal year to March 2018, though, India has said it plans to order about a quarter less Iranian crude due to a snub over development of Iran's Farzad B gas field.

“We stood by them in difficult times. We still buy substantial amounts of oil from them, and we expect reciprocity from Iran,” Indian oil minister Dharmendra Pradhan told reporters on Wednesday when asked if India was still hopeful of getting the development rights for the Farzad B field.

Following years of seeming rapprochement over the field, Iran has likely reached an agreement on the concession with Russia's state-controlled gas giant Gazprom, Russian and Indian media have reported.

Iran last month said India had not offered an acceptable proposal on the Farzad B development.

Sri Paravaikkarasu of energy consultancy FGE said India's lower Iran imports were a “reaction of Iran's decision to award the gas field to Russia and the availability of cheaper grades like those from Russia.”

India was one of four countries - China, Japan and South Korea being the other three - that continued to import large amounts of Iranian oil after sanctions were toughened in 2012.

Some of the drop in imports from Iran may be due to lower demand. Overall, India imported about 4.2 per cent less oil in May, compared with April, due to a shutdown of the 180,000-bpd Bathinda refinery for upgrades.

In the first five months of 2017, India's oil imports from Iran still jumped about 64 per cent , the data showed.

While Iran's oil exports to India are stalling, supplies to Europe and Turkey hit their highest level since the lifting of sanctions in 2016.

Iraq continued to be India's biggest oil supplier for the second month in a row in May, followed by Saudi Arabia.

Middle Eastern oil in May accounted for 65 per cent of India's overall imports, compared to 71 per cent a year ago, while the import share of Africa and Latin America have risen, the data showed.

The shift is likely a result of an effort led by the Middle East-dominated Organization of the Petroleum Exporting Countries (OPEC) to cut production to prop up oil prices.