LONDON (Reuters) - Iranian crude oil exports have fallen in May to 500,000 barrels per day (bpd) or lower, tanker data showed and industry sources said, after the United States tightened the screws on Tehran’s main source of income, deepening global supply losses.

FILE PHOTO: The Iranian flag flutters in front the International Atomic Energy Agency (IAEA) headquarters in Vienna, Austria March 4, 2019. REUTERS/Leonhard Foeger/File Photo

The United States reimposed sanctions on Iran in November after pulling out of a 2015 nuclear accord between Tehran and six world powers. Aiming to cut Iran’s sales to zero, Washington this month ended sanctions waivers importers of Iranian oil.

Iran has nonetheless sent abroad between 250,000 bpd and 500,000 bpd of oil so far in May, according to two industry sources who track the flows. Data from Refinitiv Eikon put crude shipments at about 250,000 bpd and exports of crude and condensate, a light oil, at about 400,000 bpd.

The bulk of the crude is heading for Asia, the industry sources said. It is unclear who is buying and whether the oil is heading to end-users or storage.

An Iranian official declined to comment on the export rate.

“The destinations are essentially India and China,” one of the industry sources, who declined to be identified, said. “No more to Europe or to Turkey.”

Iran’s exports have more than halved since April, when Iran shipped less than 1 million bpd. They are also less than a fifth of the more than 2.5 million bpd that Iran shipped in April 2018, the month before President Donald Trump withdrew the United States from the nuclear deal.

Iranian exports have become more opaque since U.S. sanctions returned in November. Tehran no longer reports its production figures to the Organization of the Petroleum Exporting Countries (OPEC) and there is no definitive information on exports.

Some of Iran’s oil exports are already under the radar, making it harder to assess volumes.

Crude exports of 500,000 bpd would be towards the lower end of expectations, based on comments this month from an Iranian official and an OPEC delegate.

The Iranian official, who is familiar with oil policy, had forecast exports could drop to 700,000 bpd but possibly as low as 500,000 bpd. The OPEC source said they are likely to continue at about 400,000 to 600,000 bpd.

Some analysts expect May shipments to be even less. Sara Vakhshouri, of consultancy SVB Energy International, expected exports between 200,000 bpd and 550,000 bpd.

“Iran already has plenty of stored oil and condensate in China,” she said. “So we don’t expect a significant shipment of oil in the month of May.”