Japan's crude oil imports from Iran in August fell 66.8 percent from a year earlier to 497,961 kilolitres (101,035 barrels per day), the trade ministry said on Friday, following a one-month hiatus in July, after European Union sanctions affecting insurance reduced the flow, Reuters reported.
Japanese buyers stopped lifting Iranian crude in early June, so vessels sailing the final part of their journey to Japan would be covered by insurance in early July.
Armed with a sovereign guarantee, Japanese buyers resumed loading Iranian oil in late July, with the oil arriving in Japan in August.
Japan reduced Iranian imports last month even in the face of increased oil demand after the devastating quake and tsunami last year led to the shutdown of all but two of its 50 nuclear reactors amid public fears about safety.
Japan, the world's third-biggest oil user, raised its crude imports by 2.9 percent last month from a year ago, by raising purchases from Saudi Arabia, Qatar and Kuwait among others.
For the first eight months of 2012, Japan imported 7,437,805 kl (191,731 b pd) of Iranian crude, down 42.0 percent from the same period a year ago, according to Reuters calculations based on data from the Ministry of Economy, Trade and Industry (METI).
The August data echoed figures from the Ministry of Finance showed on Thursday.
Japan is set to import about 30 percent less crude oil from Iran for the rest of this year compared with a year earlier, the president of the Petroleum Association of Japan (PAJ) said on Friday.
Japan's imports of Iranian crude oil fell to zero in July for the first time since 1981, trade ministry data showed last month, confirming Reuters projections.
Imports resumed last month as Japan's government stepped in to provide a sovereign guarantee of up to $7.6 billion a tanker for shipments to keep the oil trade with Tehran going.