A top Chinese diplomat said Tuesday war over the Iranian nuclear issue would bring disaster to the world economy and urged all nations involved to exercise restraint and prevent hostilities.

The remarks by Chen Xiaodong, a top Chinese diplomat on Middle Eastern affairs, came as Iran's showdown with the West slid closer to confrontation as alarm over its new uranium enrichment plant and Tehran's death sentence for a "CIA spy" raised the stakes.

"We urge all relevant nations to remain calm, exercise restraint, refrain from taking actions that will intensify the situation and make common efforts to prevent war," Chen said in an online interview with state media.

"Everyone knows that 40 percent of the oil shipped daily to every part of the world goes through the Strait of Hormuz, so once war starts in this region not only will the relevant nations be affected and attacked, it would also ... bring disaster to a world economy deep in crisis."

The International Atomic Energy Agency's confirmation on Monday that Iran had begun enriching uranium in a new, underground bunker southwest of Tehran was seized upon by the United States, Britain, France and Germany as an unacceptable "violation" of UN Security Council resolutions.

On Monday, a Revolutionary Court in Tehran sentenced an American former Marine, Amir Mirzai Hekmati, to death after convicting him of being a CIA spy.

The United States has called for the release of Hekmati, 28, who also holds Iranian nationality through his family who settled in the United States before his birth.

Chen's statement comes as US Treasury Secretary Timothy Geithner arrived in Beijing for talks expected to be focused on a new set of sanctions imposed by the United States on Iran late last year.

Energy-hungry China -- which relies on Iran for 11 percent of its imported oil supplies -- has repeatedly said sanctions will not resolve the nuclear issue and urged all sides to seek a diplomatic solution through dialogue.

Geithner in China for Iran sanctions talks
Beijing (AFP) Jan 10, 2012 - US Treasury Secretary Timothy Geithner arrived in Beijing on Tuesday for talks focused on sanctions against Tehran as China warned of disastrous consequences if the Iranian nuclear row escalated.

The sanctions, signed into law by President Barack Obama on December 31, intend to put further pressure on Iran, which Washington accuses of pursuing atomic weapons -- a claim denied by Tehran.

Geithner is expected to encounter stiff opposition in Beijing as Iran's showdown with the West slid closer to confrontation over its new uranium enrichment plant and Tehran's death sentence for a "CIA spy" raised the stakes.

"We urge all relevant nations to remain calm, exercise restraint, refrain from taking actions that will intensify the situation and make common efforts to prevent war," Chen Xiaodong, a top Chinese diplomat on Middle East affairs said in an online interview with the state press.

"Everyone knows that 40 percent of the oil shipped daily to every part of the world goes through the Strait of Hormuz, so once war starts in this region not only will the relevant nations be affected and attacked, it would also ... bring disaster to a world economy deep in crisis."

Chen reiterated China's rejection of the sanctions, which bar any foreign banks that do business with Iran's central bank -- responsible for processing most oil purchases in the Islamic republic -- from US financial markets.

Geithner will meet top Chinese leaders including Premier Wen Jiabao on Wednesday before heading on to Tokyo on Thursday, according to the US Treasury.

He will discuss "continued coordination with international partners in the region to increase pressure on the government of Iran, including financial measures targeting the central bank of Iran," it said in a statement.

The visit comes a day after the UN atomic watchdog said Iran had begun enriching uranium to up to 20 percent at a new plant in a fortified bunker sunk into a mountain, prompting alarm from Western powers.

But energy-hungry China -- which relies on Iran for 11 percent of its imported oil supplies -- has repeatedly said sanctions will not resolve the nuclear issue.

"If you look at it (new law) purely from the letter of the law, it really puts the US and China on a collision course," said Patrick Chovanec, associate professor at Beijing's Tsinghua University.

He said Geithner would use the visit to try to iron out differences with Beijing, which would prove a tough task.

"From a broader strategic perspective, China is very unlikely to accept the US dictating who they can buy oil from and under what conditions," he said.

An editorial published Tuesday in the state-run Global Times daily, known for its nationalist stance, said China should continue trading with Iran "despite pressure from the US and European countries."

"If Chinese companies are sanctioned by the US due to their legal trade with Iran, China should take countermeasures," the paper said.

Jia Qingguo, a professor at Peking University's American Studies Center, said China was still waiting to see whether the United States had "conclusive evidence" that Iran is developing nuclear weapons.

"If the United States asks other countries to impose joint sanctions against Iran only because it has tense ties with Iran, that's not reasonable," he said.

International sanctions, meanwhile, have left resource-poor Japan searching for alternative supplies, officials say, as Tokyo tries to respond to US and EU concerns over Iran.

Japan is heavily dependent on the Middle East for its energy, with Iranian oil accounting for nearly nine percent of its power needs in the first 11 months of 2011 -- an issue that Geithner is expected to discuss with Japanese leaders.

The treasury secretary will hold talks with Prime Minister Yoshihiko Noda and Finance Minister Jun Azumi in Tokyo on Thursday.