President Obama warned China on Tuesday that it would not be allowed to gain a competitive advantage in world trade by "skirting the rules."

Making an election-year pitch to American workers, and businesses as well, Obama said Washington has brought a new trade case against Beijing. The goal is to pressure China, a rising Asian economic power, to end its restrictions on exports of key materials used to manufacture hybrid car batteries, flat-screen televisions and other high-tech goods.

"If China would simply let the market work on its own, we'd have no objection," Obama said during remarks in the White House Rose Garden. "But their policies currently are preventing that from happening. And they go against the very rules that China agreed to follow."

The United States, working in conjunction with the European Union and Japan, asked the World Trade Organization on Tuesday to facilitate talks with China over its curtailment of exports of what's known as rare earth minerals. Obama cast the fresh action against China as part of a broader push to level the playing field for U.S. companies.

"When it is necessary, I will take action if our workers and our businesses are being subjected to unfair practices," Obama said.

China has a stranglehold on the global supply of 17 rare earth minerals that are essential for making high-tech goods, including hybrid cars, weapons, flat-screen TVs, mobile phones, mercury-vapor lights, smart phones and camera lenses. The materials also are used in the manufacture of tiny motors, such as those used to raise and lower car windows and in consumer electronics.

"America's workers and manufacturers are being hurt in both established and budding industrial sectors by these policies," U.S. Trade Representative Ron Kirk said in a statement. "China continues to make its export restraints more restrictive, resulting in massive distortions and harmful disruptions in supply chains for these materials throughout the global marketplace."

On Tuesday, a Chinese foreign ministry spokesman defended Beijing's curbs on rare earth production as necessary to limit environmental damage and conserve scarce resources.