A spokeswoman for the Coalition for American Solar Manufacturing said the group had set a news conference for early Wednesday afternoon to announce a new trade case.

She declined to identify the country targeted in the complaint but it is widely expected to be China, which has shown itself to be a fierce competitor in the worldwide battle for solar panel market share.

The U.S. solar industry has been hit hard by competition from China and other countries that U.S. companies accuse of providing cheap financing and subsidies to support the sector.

At the same time, some trade experts have warned that the Obama administration needs to tread carefully since the United States also has programs to support the sector.

Last month, U.S. solar panel maker Solyndra filed for bankruptcy, burdened with $783 million in secured debt and squeezed by falling prices caused by an industry glut.

Its downfall has become a political embarrassment for the Obama administration, which had promoted it as an example of how it planned to spur development in clean energy technology and provided a government guarantee on a $535 million loan Solyndra has said it may not repay in full.

Oregon Senators Ron Wyden and Jeff Merkley are expected at Wednesday's press conference along with Gordon Brinser, president of SolarWorld Industries, headquartered in Hillsboro, Oregon, which bills itself as the largest U.S. solar manufacturer.

Last month, Wyden urged President Barack Obama to use U.S. trade law to restrict solar panel imports from China.

"The American solar industry is facing unparalleled challenges and without the leadership of your administration this industry may disappear," Wyden said in a letter.

Still, Representative Sander Levin, a Michigan Democrat, warned Friday after meeting with U.S. solar industry representatives there could be no American-made solar panels within five years unless the U.S. government took action against unfairly priced imports.

While industries such as steel have relied heavily on U.S. anti-dumping actions to restrict foreign competition, the solar case appeared to be the first time the renewable energy sector has turned to U.S. trade remedy laws.

However, the Obama administration did successfully challenge a number of Chinese subsidies to support its wind power producers in a World Trade Organization case initiated by the United Steelworkers union.