(Bloomberg) -- Attorneys advising a group of U.S. solar manufacturers said it filed petitions requesting federal investigations into Chinese firms circumventing tariffs by manufacturing in other countries including Malaysia, Vietnam and Thailand.

The group -- called the American Solar Manufacturers Against Chinese Circumvention -- filed the petitions with the U.S. Department of Commerce, according to Wiley Rein LLP, a Washington D.C. law firm advising the companies. Spokespersons for the department didn’t immediately respond to emailed requests for comment sent outside of normal working hours.

Chinese firms dominate the manufacture of photovoltaic panels, which is a multi-step process often done in separate factories that can be located in different provinces or even countries. Several companies have opened plants in other nations in recent years for the last stage, assembling the solar modules.

The petitions argue that this creates an obvious route to circumvent U.S. tariffs against Chinese solar products. The industry group is asking for the extension of those tariffs to cover products from factories built by Chinese companies in Southeast Asia.

The call from the American companies comes amid increased U.S. pressure against China’s solar industry as the Biden administration cracks down on alleged labor abuses in the Xinjiang region. Canadian Solar Inc. warned this week that all panel imports from China risk being detained by U.S. Customs.

The petitions name several of China’s largest solar manufacturers, including Longi Green Energy Technology Co., Trina Solar Co., JinkoSolar Holding Co. and JA Solar Technology Co.

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