Factory labor built China into the world's third largest economy, after the United States and Japan. Now something else is building: labor tensions.

China bars labor unions independent of the Communist Party. But George Haley at the University of New Haven in Connecticut says labor unrest is common.

GEORGE HALEY: "This really isn't new. There has been a tremendous amount ofagitation among workers for higher pay for years."

Disputes are especially common in the Pearl River manufacturing area in southeastern China. Companies there have resisted raising wages.