NEW DELHI- India's oil imports from Iran fell about 57 percent year-on-year in April, according to tanker arrival data seen by Reuters, the last month when New Delhi was allowed to load Iranian oil ahead of U.S. sanctions stopping purchases of oil from the OPEC member.

India, Iran's top oil client after China, shipped in about 277,600 barrels per day (bpd) of oil from Tehran in April, down about 31.5 percent from the previous month, preliminary tanker arrival data from shipping and industry sources showed.

The United States introduced sanctions in November but gave a six-month waiver to eight nations, including India, which allowed them to import some Iranian oil.

India was allowed to buy an average 300,000 bpd of oil during November-April, but actual volumes varied from month to month due to lack of ships after foreign shipping lines backed out of Iranian deals under pressure from U.S. sanctions.

In April, Washington asked buyers of Iranian oil, mostly in Asia, to halt purchases or face sanctions.

India is scheduled to get two very large crude carriers carrying 4 million barrels of Iranian oil this month - one each at Paradip in the east and Kochi in the west. The two vessels were loaded in April.

Since November, when India received the sanctions waiver, only state-run Indian Oil Corp, Bharat Petroleum Corp, Hindustan Petroleum and Mangalore Refinery and Petrochemicals  have been buying Iranian oil.

India's overall imports from Iran in January to April 2019 fell nearly 45 percent to 304,500 bpd compared with 552,000 bpd a year ago, the data showed.

The sources declined to be identified as they were not authorised to speak with media.

(Reporting by Nidhi Verma; Editing by Mark Potter) ((; +91 11 49548031; Reuters Messaging: