The US will challenge Chinese duties imposed on imported American vehicles, in a counter-strike timed to coincide with Barack’s Obama’s tour of manufacturing states that will be pivotal in the presidential election.

The “enforcement action” allows the US to demand formal consultations with China at the World Trade Organisation in Geneva.

Mitt Romney, Mr Obama’s Republican challenger, has accused him of not standing up to China on trade. Mr Obama told crowds in Ohio: “As long as we are competing on a fair playing field, we are doing just fine – and I am going to make sure the competition is fair,” China’s rise is looming as an important election factor in industrial states, where the Asian giant is often depicted as an unfair trader that is hollowing out local manufacturing.