U.S. President Barack Obama says China has been “gaming” the international trading system by intervening in the foreign exchange markets to make its currency cheaper.

He says the action hurts U.S. companies by making their goods more expensive in China and giving Chinese-made goods a price advantage on U.S. markets.

Mr. Obama spoke Thursday in Washington shortly after the Senate approved a procedural step advancing a bill intended to retaliate against China's alleged currency manipulation.

Mr. Obama said his administration has been “aggressive” in fighting for U.S. exporters, but says he is concerned that the bill currently in the Senate may violate U.S. treaty obligations, or spark retaliation from China without solving the currency problem.

The currency bill might be brought to a final Senate vote Thursday. The measure may pass the Democrat-controlled Senate, but faces stronger opposition in the House of Representatives, where Republicans are in charge.