Iranian President Mahmoud Ahmadinejad accused the United States of hypocrisy during a visit to the World Expo in Shanghai.<br/><br/>He, however praised his host and ally China which backed new nuclear sanctions against Tehran.<br/><br/>Ahmadinejad said countries already possessing nuclear weapons were unwilling to let other nations develop peaceful nuclear energy. He describes such nuclear-armed countries as criminals who spread rumors to create what he says are obstacles to prevent others from using peaceful nuclear power.<br/><br/>China had opposed more UN sanctions against one of its major oil suppliers. But under mounting international pressure, Beijing made a U-turn Wednesday by voting for a fourth round of sanctions on Tehran over its nuclear program. It did so after working with Russia to water down the sanctions.<br/><br/>President Ahmadinejad is not scheduled to meet any Chinese leaders while in the country.