China has overtaken the European Union to become Iran’s largest trading partner, according to a new analysis of the commercial ties between the two countries.

The growing business links between Beijing and Tehran underline China’s reluctance to agree to any further economic sanctions on Iran as western countries escalate their campaign to contain the country’s nuclear ambitions.

Official figures say the EU remains Tehran’s largest commercial partner, with trade totalling $35bn in 2008, compared with $29bn with China.

But this number disguises the fact that much of Iran’s trade with the United Arab Emirates consists of goods channelled to or from China. Majid-Reza Hariri, deputy head of the Iran-China Chamber of Commerce, said that transhipments to China accounted for more than half of Tehran’s $15bn (€10.9bn, £9.6bn) trade with the UAE.

When this is taken into account, China’s trade with Iran totals at least $36.5bn, which could be more than with the entire EU bloc. No definite conclusion is possible because it is unclear how much of Iran’s trade with Europe is channelled via the UAE.

Iran imports consumer goods and machinery from China and exports oil, gas, and petrochemicals.

Today, China depends on Iran for 11 per cent of its energy needs, according to the chamber.