WASHINGTON (AP) — The Obama administration is signaling it plans to take a tougher stance with China on trade issues, including demanding that Beijing move more quickly to reform its currency system.

As part of that new approach, the administration filed two new trade cases against China before the World Trade Organisation and Treasury Secretary Timothy Geithner said China must move faster to allow its currency to rise in value against the dollar.

In testimony prepared for two congressional hearings yesterday, Geithner criticised a variety of Chinese economic policies from Beijing's currency system to what he said was rampant piracy of US products and the erection of numerous barriers that prevent US companies from operating in China.

"We are very concerned about the negative impact of these policies on our economic interests," Geithner said in testimony prepared for hearings of the Senate Banking Committee and the House Ways and Means Committee.

His comments come at a time of growing US unhappiness with Chinese economic practices, which critics contend have led to huge US trade deficits with China and the loss of millions of American manufacturing jobs over the past decade.

Chinese Foreign Ministry spokeswoman Jiang Yu yesterday rejected Geithner's criticism, saying appreciation of the yuan "can't solve the trade deficit with China".

She added: "Pressure cannot solve the issue. Rather, it may lead to the contrary."

Lawmakers in both the Senate and House, responding to voters unhappy with painfully high unemployment in the United States following a deep recession, are pushing legislation that would expand the government's power to impose trade sanctions on China.

Geithner, while not endorsing the new legislation, said that the administration was committed to "using all tools available to ensure that American firms and workers can trade and compete fairly with China."

On Wednesday, US Trade Representative Ron Kirk announced that the administration was filing two new trade cases against China before the Geneva-based WTO, which oversees the rules of global trade.

In one of the WTO cases, the administration said China was discriminating against US credit and debt card companies in favor of a state-owned financial services firm. The other case contended that China had improperly imposed trade sanctions on a type of US-made flat-rolled steel used in electric transformers, reactors and other types of power-generating equipment.

The two trade cases filed by Kirk's office could lead to retaliatory US sanctions against Chinese products if the WTO rules in favour of the US complaints.

In Beijing, Chinese government officials said there would be no immediate reaction to the new trade cases or to Geithner's comments.