WASHINGTON — 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 announced 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 U.S., working in conjunction with the European Union and Japan, asked the World Trade Organization 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.

With the U.S economy slowly recovering from recession, Obama has sought to bring a renewed focus on Chinese policies that could hinder U.S. expansion. He used an executive order last month to create a new trade enforcement agency – the Interagency Trade Enforcement Center – to move aggressively against China and other nations.

Obama’s posture on China has already surfaced as an election-year issue, with Republican front-runner Mitt Romney criticizing him for refusing so far to cite China for manipulating its currency. Romney has said he would label China a currency manipulator on his first day in office, a move that could lead to trade sanctions against Beijing.

The White House insisted that Tuesday’s announcement was not intended to be a counter to Republican criticism.

“The president’s commitment on this has been evident from the very beginning, and this is simply part of that effort,” White House spokesman Jay Carney 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, smartphones 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.

China has reduced its export quotas of these rare earth minerals over the past several years to cope with a growing demand during rapid business expansion at home, although Chinese officials also cite environmental concerns as the reason for the restrictions. U.S. industry officials suggest it is an unfair trade practice that violates rules established by the WTO, a group that includes China as a member.

Administration officials said Beijing’s export restrictions give Chinese companies a competitive advantage by providing them access to more of these rare earth materials at a cheaper price, while forcing U.S. companies to manage with a smaller, more costly supply.

“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.

“We think the policy is in line with WTO rules,” the spokesman, Liu Weimin, said at a briefing.