The discussions in Geneva involving China, Russia, the US and leading European powers were followed by a warning to Iran that it had a fortnight to respond positively or face fresh sanctions.

To pave the way for substantive negotiations, the big powers offered to suspend moves to tighten sanctions in return for a commitment from Iran not to expand its uranium enrichment any further. Iran insists the program is not for nuclear weapons, but to produce fuel for atomic reactors to generate electricity. The five permanent members of the United Nations Security Council plus Germany regard agreement on their ''freeze-for-freeze'' proposal as a necessary step before talks with Iran on a wider package of economic and diplomatic incentives. However, Iranian stonewalling continues to reinforce suspicions that it is trying to buy time while pursuing a clandestine bomb-making program and exploiting differences among the key powers.

Perhaps the most important of these differences revolves around the web of ties that China and Russia have with Iran in energy, trade, investment and arms supplies. Yet while Russia a major energy exporter has an interest in a simmering Iran problem that helps keep the US preoccupied and the oil price high, China a major energy importer is suffering from the doubling of oil costs in the past 12 months, which has stoked inflation and forced the Government to approve unpopular rises in petrol, diesel and electricity prices.

Sometime this year, if it has not already happened, China will pass a milestone in its increasingly precarious effort to sustain energy security. More than half its crude oil will be imported and this dependence is forecast to rise to 80 per cent in 2030. Already, a big majority of China's oil imports come from volatile areas of the Middle East and Africa, chiefly the Persian Gulf. This is an unsettling experience for China, which until 1993 was self-sufficient in oil, its main source of transport fuel for a rapidly expanding economy.

Foreign dependence is making China take a more intense interest in what happens in the Middle East and Africa. And since almost all the oil it imports from there is shipped in tankers to China via South-East Asia, Beijing's interest in the security of sea lanes and vital shipping straits particularly the Malacca and Singapore straits, the South China Sea and the Taiwan Strait will only increase. Protection of energy supplies is also one factor drawing the Chinese Navy into the Indian Ocean, to the alarm of India.

Nearly 45 per cent of China's crude oil imports come from the Middle East and more than 30 per cent from Africa. The two biggest Middle East suppliers are Saudi Arabia, with a 16per cent share of China's oil imports, and Iran, with a somewhat smaller share. China has so far balanced its relations with oil- and gas-rich Iran, on the one side. On the other, US-backed Saudi Arabia and the other five Arab states in the Gulf Cooperation Council, the GCC, on the western side of the Gulf worry about Iranian domination of region and the tumultuous consequences if Tehran gets nuclear weapons.

This balancing act will become harder for China to maintain in future. The International Energy Agency expects that China will be relying on the Middle East for 70 per cent of its oil imports by 2015, up from 44 per cent in 2006. Most of the new oil is likely to come from GCC producers. While GCC oil and natural gas development has been expanding in recent years, Iran's has been increasingly constricted by a combination of bad policy and foreign sanctions that deny it Western investment and advanced technology.

Meanwhile, two-way trade and investment between the GCC and China is booming. In April, for example, the state-controlled energy giant PetroChina agreed to buy three million metric tons of liquefied natural gas from GCC member Qatar over 25 years in a deal worth at least $US60 billion. Qatar's foreign partner in the project is Royal Dutch Shell.

What could prompt China to side more openly with the West and the GCC in the dispute with Iran? Of course, China, like Russia, does not want to damage its energy and commercial interests in Iran, which has the potential to become an even bigger exporter of oil than it is at present, and a huge exporter of gas, to Asia and the rest of the world.