China cannot rest on its laurels after the steps it has taken to liberalise its economy during its first five years in the World Trade Organisation and it needs to move forward, US Undersecretary of Commerce Frank Lavin said.

"In a number of critical sectors there has been little to no progress in market opening," Lavin told an audience of US businesspeople in Beijing.

"Our point is that the world economy is moving, so we should always look ahead. We can't simply say in 2002, we fixed a problem, in 2004 we fixed another problem. We have to say, what are we fixing in '07 and '08."

China accounted for 28 percent of the US record 763.6 billion-dollar deficit in 2006 and Lavin warned that concerns in Washington about the imbalance were growing stronger.

"The atmosphere on US-China trade issues is probably more negative now than at any time I've ever seen," Lavin said.

The yawning trade surplus has led to American calls for more open trade and a rise in the Chinese currency to erase some of the alleged unfair advantages enjoyed by the Asian giant's exporters.

The undersecretary mentioned barriers to business in sectors ranging from telecom to civil aviation, saying US carriers were eager to open up new routes to China.

"If there is that kind of demand (in aviation), let's just liberalise. Why not just open them all up?" he said.