The amount of oil imported to India from Iran decreased in June, according to new data from industry sources.

Some 592,800 barrels per day (bpd) was brought into the Asian nation last month, down by 15.9 per cent from 705,200 bpd in May.

Although state refiners increased their Iranian volumes by ten per cent to around 454,000 bpd, the total was dragged down by a decline in imports from private refinery purchases.

This is the first month data has been available since the US said it would be reimposing sanctions on Iran following America's withdrawal from the 2015 agreement with Iran, Russia, China, France, Germany and Britain to cut nuclear activity.

US sanctions on oil and transactions with the Central Bank of Iran are to come into effect in early November, with India and other countries instructed to decrease their oil imports from Iran to zero or face penalties themselves.

India is Iran's top client for oil after China, but it has been asking refineries to look for alternative places to buy the fossil fuel as it seeks to comply with the US requirements.

Oil imports from Iran had already been cut in 2017-18 after a dispute over development rights for an Iranian natural gas field, but Iran offered free shipping and an extended credit period, so they were raised again.

Last month, Reuters reported that India may be seeking to sign an agreement that would mean it could pay Iran for oil in rupees in a bid to avoid the US sanctions.

Meanwhile, India's Foreign Minister Sushma Swaraj has insisted India will keep trading with Iran and will only follow sanctions from the United Nations.

Iran has allegedly struck back at India over the threats to cut imports, with Deputy Ambassador Massoud Rezvanian Rahaghi quoted as saying the Asian nation would lose "special privileges" if it did so.

Mr Rahaghi insisted Iran follows a "rationale pricing" and has always been a reliable energy partner for India.