China has criticised the United States for imposing sanctions on a state-run oil firm for exporting petroleum products to Iran, saying the move was "without reason". Washington on Thursday slapped sanctions on China's Zhuhai Zhenrong Co., barring it from doing business in the United States, saying it brokered delivery of more than $500 million worth of gasoline to Iran from July 2010-January 2011. "We express strong dissatisfaction and firm opposition to this," foreign ministry spokesman Liu Weimin said in a statement carried by the official Xinhua news agency late Saturday. The sanctions, also placed on companies from Singapore and the United Arab Emirates, bar the three firms from receiving US export licenses, trade support from the US Export Import Bank, and loans over $10 million from US financial institutions. Liu said China's cooperation with Iran was similar to other countries. "Like many other countries, China maintains normal cooperation with Iran in energy, economic and trade fields," he said, adding that the US had acted unilaterally to impose the sanctions. "This is without reason, and against the content and spirit of resolutions by the United Nations Security Council on the Iran nuclear issue." Chinese state media Saturday quoted the company as dismissing the US claims as "fiction", with an official saying the firm doesn't export refined oil to Iran. The US sanctions came shortly after US Treasury Secretary Timothy Geithner met Chinese leaders in Beijing to ask for help in squeezing Iran's key oil revenues and pushing Tehran to halt its nuclear ambitions. But China, long an important buyer of Iranian oil, has resisted adding its weight to the US and European campaign. Chinese officials have warned against making links between China's trade relations with Iran and the issue of Tehran's nuclear program.