China's imports of Iranian crude in April more than doubled from a year ago to a record near 800,000 barrels per day (bpd).
China's imports, added to India's shipments of about 225,000 bpd in April and South Korea's 135,000 bpd, put Asia's purchases of Iranian crude for last month over the 1 million bpd limit - with Japan still to report its oil import data later in May, Reuters reported on Wednesday.
Under the temporary deal that went into effect in January, Iran's exports are supposed to be held at an average 1 million bpd for the six months to July 20, but shipments arriving in Asia have topped that mark since November, according to customs and ship tracking data.
China's crude imports from Iran in April rose 115.3 percent to 799,865 bpd, customs data showed on Wednesday, accelerating a rise in its intake from the OPEC member after the November nuclear deal that eased some sanctions on Tehran.
On a daily basis, China's April imports of Iranian oil rose 44 percent from March's 555,182 bpd.
The jump in the Iranian oil purchases was part of a 21 percent rise in China's total crude imports in April from a year ago to a record of 6.78 million bpd, official data showed earlier. The increases have come on higher seasonal demand and indications of stockpiling, according to analysts.
"Imports from Iran are likely to be higher this year ... part of (China's) stockpiling efforts," Michal Meidan, the Director of independent consultancy China Matters told Reuters Global Oil Forum.
China's oil arrivals from Iran in the first four months of this year were at 618,170 bpd, up 54.5 percent from a year ago.
China's high oil imports and moderate growth in oil demand could suggest stockpiling in both commercial and strategic reserves as some of its second phase tanks for strategic reserves have finished construction, analysts said.
China's imports from Iran have also been higher this year due to new volumes of condensate, a super light crude, and because top refiner Sinopec Corp may have boosted liftings under a long-term agreement, traders said.
Condensate imports are likely to be between one to two very large crude carriers (VLCCs) per month, or between 67,000 and 133,000 bpd, said a Chinese crude oil trader.
Condensate is included in China's crude oil imports, but a US State Department spokeswoman confirmed in April that the light oil is exempt from sanctions.
China may have trouble holding down its Iranian oil imports in 2014 as state-run trader Zhuhai Zhenrong Corp is negotiating a new condensate contract to supply an independent petrochemical firm Dragon Aromatics.
Dragon Aromatics has since the second half of 2013 been buying condensate from Iran as feedstock.