But May imports are up 34.5 percent, or 133,902 bpd from 388,034 bpd in April after Iran and Beijing resolved disputes over annual contracts.
In the January-May period, China's crude imports from Iran totalled 389,857 bpd, down 25 percent from a year earlier.
Unipec, the trading arm of top Asian refiner China Petroleum & Chemical Corp (Sinopec) , will buy up to a fifth less crude from Iran under an annual contract for 2012 versus last year, a Chinese industry executive with direct knowledge of the matter told Reuters.
Industry sources said the decline was mostly because Sinopec slashed imports in the first quarter by about 285,000 bpd, just over half of daily imports in 2011, as the two haggled over pricing terms against a backdrop of rising international pressure on Tehran.