Customs data released today by Beijing shows China's imports of Iranian crude oil shrank by nearly 40 percent during January and February compared to the same months a year earlier.
The drop comes despite China's expanding hunger for foreign oil.
The data shows that Iran has slipped from being China's third to fourth biggest foreign supplier of crude oil -- overtaken by Russia during the first two months of 2010. China's crude shipments from its number one supplier -- Saudi Arabia -- rose 5.4 percent during January and February.
Iran was the only major crude oil supplier to China to show a fall in deliveries.
The drop comes as Western powers urge Beijing to approve proposed new United Nations Security Council sanctions against Tehran over its disputed nuclear activities.