China’s imports of Iranian crude oil fell by almost a third in the first half of the year, new figures showed this week.

Volumes have decreased just as new US and European sanctions threaten to disrupt energy ties between the two countries, experts say.

Iran shipped just over 9 million barrels of oil to China to the end of last month, making it China’s third-largest crude supplier, according to fresh Chinese customs data. That was down from 13.1 million barrels in the first half of last year, even as Chinese imports from Angola, Saudi Arabia and other major exporters rose significantly.

“In May 2009, Iran was the number one supplier to China,” said Afshin Molavi, an Iran expert at the New America Foundation, a think tank in Washington. “There is a lot of talk about whether this is a political decision by China or whether it’s simply a pricing matter. We don’t have a definitive conclusion on that yet.”

Iran enticed China to buy its crude and invest in its energy sector as European companies reduced their operations in the country and the Russian government pressured Tehran to curtail its nuclear programme. US companies have not been present in Iran for decades.

The result is that Iran needs China more as a partner than China needs Iran, Mr Molavi said at a recent conference on Iran at the Woodrow Wilson International Centre in the US capital. The nature of the relationship is illustrated by the fact that hardly any of the US$80 billion (Dh293.83bn) to $100bn worth of investment agreements with Chinese companies reported by Iranian media have been finalised, he said.