The US called upon China to step-up economic reforms but Beijing responded by saying that trade relations should not be politicized as the second round of the countries' strategic economic dialogue kicked off on Tuesday in Washington, AFP reported. In his opening remarks, US Treasury Secretary Henry Paulson said the policy disagreements "are not about the direction of change but about the pace of change," as he stressed that China must address some "persistent trade and financial imbalances." American concerns focus upon an escalating trade deficit with China, said to be fueled by Beijing keeping the value of its currency artificially low so that exports are comparatively cheaper. Chinese Vice Premier Wu Yi, who heads a delegation of 15 cabinet ministers at the talks, was blunt in her response. "Politicizing trade and economic issues is absolutely unacceptable," she said, arguing that "problems and controversies should be handled calmly and addressed according to economic law." Repeating her theme from the first round of talks, Wu said that China and the US were at different stages of development and this must be taken into account. She also called on Washington to relax export controls on high-tech products.