Iran has steadily increased its export of crude oil since November 2013 as global demand for its energy supplies rose, the International Energy Agency announced, adding that China's purchase of Iranian crude has now returned to pre-sanctions level. "Iran’s top oil importers have bought more than 1 million bpd since November, making February the fourth straight month in which Tehran’s oil exports increased despite Western sanctions," the IEA said in a report on Wednesday. February crude loadings by Iran's top four buyers - China, India, Japan and South Korea - rose to 1.16 million bpd. China imported 502,500 bpd of Iranian crude oil last month, taking its purchases back to pre-sanctions levels. The Asian country received 564,536 bpd in January. Meanwhile, China’s state-run trader Zhuhai Zhenrong Corp has announced that it is negotiating a new condensate contract with Tehran, which could increase crude import from Iran even more in 2014. India, Iran’s second-biggest client bought 304,286 bpd of crude in February and 412,000 bpd in January. South Korea imported 1.1 million tons of Iranian crude in February, equivalent to 294,069 barrels per day, showing an increase of 104 percent compared to the same period last year. Including Turkey, Iran's crude and condensate exports rose to 1.37 million bpd in February, up by 74,000 bpd from January, said the report. An interim accord easing restrictions on insurance for Iran’s oil shipments and freeing up cash held outside the country in return for Iran’s more cooperation to address Western concerns over its nuclear program went into effect last month. Under the agreement, six buyers permitted under US sanctions to take Iranian crude don’t have to cut imports to avoid penalties. Iran had an estimated 30 million barrels of crude held on tankers at the end of January, including 6 million barrels in vessels off China’s coast, according to the report. Total production rose by 30,000 barrels to 2.78 million last month, as cold winter weather in Iran boosted domestic fuel use. The six buyers permitted to import Iranian crude under US sanctions are Turkey, China, Japan, India, South Korea and Taiwan.