The US Commerce Department confirmed yesterday it will launch a formal investigation into imports of wind turbine towers from China and Vietnam, further escalating tensions between the US and Asian economies over the level of subsidy offered to clean technologies.

The investigation mirrors an ongoing probe into Chinese solar panel manufacturers. It will assess whether Chinese and Vietnamese wind turbine tower firms are guilty of breaching trade rules by dumping low-cost towers in the US market, undercutting domestic manufacturers.

If the Department rules that China and Vietnam are engaging in unfair trade practices, it could move to impose steep import duties on turbine towers. This would further escalate the long-simmering row over the level of support Asian economies are providing to clean-technology firms.

According to Reuters’ reports, towers from China and Vietnam imported to the US during 2010 were worth $103.6m and $51.9m, respectively.

However, a group of US producers, including Broadwind Energy Inc., DMI Industries and Katana Summit, have alleged that overseas competitors are taking advantage of unfair subsidies that allow them to significantly undercut their products.

But lawyers acting on behalf of a group of Chinese and Vietnamese firms countered that wind turbine tower suppliers are selected based on a wide range of factors besides costs. It claimed that towers are being imported because they are best suited to wind farm developers’ needs.

In other industry news, Spanish wind turbine manufacturer Gamesa announced this week that it has secured an order from Chinese wind farm developer Langyuan to supply 50MW of turbines to a project in Ningxia.

The company said that the deal followed a similar order last year and takes its development pipeline in China to nearly 3GW.