She stood close to a parade of closed shops and pawnbrokers in North Carolina as she vowed to turn the US economy around, despite fears of recession, and promised action to reverse a tide of industrial jobs moving abroad.

"We do have to get tough on China, it is long past time for us to blow the whistle," the New York senator said, in the latest of a string of campaign assaults on Beijing.

"This country manipulates its currency to our disadvantage, they engage in broad-based intellectual property theft, industrial espionage, they do not follow the rules they agreed to follow when they joined the WTO," she said.

"What do we get in return from them? Well, we get tainted pet food, we get lead-laced toys, we get polluted pharmaceuticals."

"If you want to be our partner, you've got to play by the same rules," Clinton said, three days before North Carolina's crucial primary, one of the key end-game votes in the Democratic nominating contest.

The American Manufacturing Trade Action Coalition says North Carolina, in the eastern United States, has lost 211,000 manufacturing jobs since 2001.

The area around Gastonia, a traditional hub of heavy industry, lost over 25,000 manufacturing jobs during the same time.