The United States says it plans to impose new tariffs on Chinese solar companies, ruling they are flooding the U.S. market with solar panels at prices below the cost of production.

The Commerce Department on Thursday announced duties as high as 31 percent on Chinese-made solar panels. The move is meant to boost the U.S. solar manufacturing industry, which has struggled against Chinese competition.

This would be on top of previous tariffs ranging from 2.9 percent to 4.7 percent imposed in March because of what the U.S. says is unfair Chinese government subsidies for solar power equipment.

Although the move was expected, it could raise tensions between the world's two largest economies, which have squared off on a number of other trade disputes in recent months.

Some critics also warn that the decision could make solar panels more expensive for U.S. customers, saying Chinese companies may raise prices of their equipment in order to make a larger profit.

The Commerce Department is expected to confirm Thursday's preliminary ruling in October.