Japan's crude imports from Iran fell 65.5 percent in April from a year earlier, ahead of an even deeper fall expected in May and June due to difficulty in doing business with the Islamic Republic amid tighter Western sanctions, Reuters reported.
The double-digit decline was partly because of the timing of shipments clearing customs. Last month, Ministry of Finance trade data showed customs-cleared crude imports from Iran fell only 6.3 percent in March from a year earlier.
The falls came even after Japan secured in March a six-month waiver from U.S. financial sanctions relating to Iran, and despite an increase in overall oil demand after last year's Fukushima nuclear disaster.
Japan will slash its crude purchases from Iran by almost 80 percent in April from the first two months of the year, as buyers comply with sanctions that make it tough to pay, ship and insure the oil.
The ships loading in April will arrive in Japan in May or later.
Looking ahead, the European Union's sanctions on Iran, due to take effect in July, are making it impossible for Japanese buyers to find insurance cover for ships carrying Iranian oil because they rely on European insurers and reinsurers.
Government officials have said Tokyo may provide the cover if its lobbying fails to convince the EU that it should remain exempt from a ban on insurance and reinsurance of Iranian crude imports.
Wednesday's data showed crude imports from Iran in April totalled 564,962 kilolitres (118,450 barrels per day), down 65.5 percent on a year earlier and down 67.7 percent from March's 1,751,737 kl (355,422 bpd).
More-closely watched monthly data from the Ministry of Economy, Trade and Industry on the country's demand and imports of oil is due on Thursday.
The METI data take into account shipments to refineries and oil terminals and often differs from the customs data.