The US, the European Union and Canada could file a joint complaint with the World Trade Organization against China's import tariffs on auto parts as early as this week, the Wall Street Journal reported, citing people familiar with the matter. It will be the first time the Western allies have teamed up to seek a formal investigation by the global trade body in a dispute with the Asian giant. The three governments filed a preliminary complaint against Chinese protection of its auto-parts manufacturers in March but China has refused to change its policy, which charges an average 25% levy on imported auto parts. That leaves formal complaint at the WTO as a last recourse for Washington, Brussels and Ottawa. The US exported only about US$540 million of auto parts to China last year, a market estimated at US$19 billion, and the EU says its auto-parts exports to China are valued at about US$4 billion. The complaint could result in punitive special tariffs being imposed on Beijing.