China faces growing pressure from Western countries to back fresh sanctions against Iran over its disputed nuclear activities. Here are key facts about ties between China and Iran.
IRAN A BIG OIL SUPPLIER, BUT NOT THE BIGGEST
Iran is the third-biggest foreign supplier of crude oil to China, the world's second-biggest consumer of oil.
But China's crude flows from Iran are much smaller than those from Angola and the top ranked supplier, Saudi Arabia.
Iran shipped 23.1 million metric tonnes of crude to China in 2009 -- 11.4 percent of China's total crude imports for that year. Angola supplied 32.2 million tonnes, and Saudi Arabia 41.9 million tonnes.
China's crude imports from Iran in 2010 will at least stay at the same level as in 2009, Wang Tianpu, president of Sinopec, a major Chinese refiner, said late last year.
China is not the only Asian economy tied to Iranian oil. In 2008, Japan was the world's biggest buyer of Iranian crude exports, with China second and India third, according to the U.S. Energy Information Administration.
CHINA'S ENERGY, TRADE STAKES IN IRAN
Trade between China and Iran has grown quickly, dominated by Iran's energy exports.
In 2005, bilateral trade was worth $10.1 billion. In 2009, it was worth $21.2 billion, a fall of 23.6 percent from 2008, reflecting the falling dollar value of oil.
China's exports to Iran in 2009 were worth $7.9 billion, a decline of 3.0 percent from 2008. Main Chinese exports to Iran include machinery and equipment, motor vehicles, textiles and consumer goods.
China is also a big investor in Iranian oil and gas, and Chinese state-owned energy conglomerates are keen to extend invest in oil refining facilities in Iran.
China's top energy group, CNPC, this month clinched a deal to develop phase 11 of Iran's South Pars gas project and expand its operations in the Islamic Republic.
In the oil sector, CNPC is already in a deal to develop Iran's North Azadegan field into a 120,000-barrel per day field at a cost of at least $2 billion.
China's Sinopec Group reached a $2 billion deal to develop Iran's Yadavaran oil field in December 2007.
Industry sources have said China has been selling gasoline to Iran, which lacks refining capacity to meet domestic demand, despite plentiful unrefined oil. Chinese customs statistics do not record any shipments, which may go through intermediaries.
CHINA A CLOSE DIPLOMATIC PARTNER
China has kept close bilateral ties with Iran, but also backed U.N. Security Council resolutions critical of Tehran's stance on nuclear issues.
Western powers criticized the disputed election of June 2009 that kept President Mahmoud Ahmadinejad in power and condemned violence and arrests directed at subsequent anti-government protests.
By contrast, China has not openly criticized the Iranian government, and a top Chinese state newspaper last month accused the United States of using the Internet to foment unrest in Iran.
In October last year, Chinese Premier Wen Jiabao told the visiting First Vice President of Iran, Mohammad Reza Rahimi, that his government wanted to maintain high-level contacts with Tehran.
CHINA WORRIED BY NUCLEAR PLANS, BUT WANTS TALK, NOT SANCTIONS
But China's support for Iran is not unreserved. Beijing is seeking to cast itself as a responsible supporter of nuclear non-proliferation and has voted for U.N. Security Council resolutions pressuring Iran.
Beijing also faces other Middle East countries, including Saudi Arabia, worried about Iran's nuclear program.
China has followed a pattern of approving U.N. decisions critical of Tehran, but resisting sanctions that could hurt its energy and economic ties with Iran.
In July 2006, China backed U.N. Security Council Resolution 1696 that threatened sanctions on Iran, and in December of the same year it supported Resolution 1737, which put sanctions on Iranian nuclear imports and exports.
In March 2007, China backed Resolution 1747, which broadened sanctions to cover a ban on Iranian arms exports.
In March 2008, China backed Resolution 1803, which criticized Iran for refusing to suspend uranium enrichment, and urged governments to exercise vigilance against Iranian people and banks suspected of involvement in illicit nuclear activities.
In November 2009, China supported a resolution by the International Atomic Energy Agency board of governors that criticized Iran for secretive uranium enrichment activities.
(Reporting by Chris Buckley)