Republican presidential front-runner Donald Trump bashed Boeing Co. on Wednesday over its plans to open a new facility in China that the company's largest union says could hurt American workers.

Boeing announced on Wednesday a deal to sell China 300 new aircraft. It is also expected to unveil an agreement to open a new facility there that would finish and deliver 737s built at Boeing's factory in Renton, Washington.

"Boeing is going to sell 300 jets to China, but as part of the deal, they're going to set up a massive plant in a big section of China," Trump said during a speech before African-American business leaders in North Charleston, South Carolina.

"That will end up taking a tremendous number of jobs away from the United States," he said.

Trump's comments came on the same day Chinese President Xi Jinping toured Boeing's Everett, Washington, factory. The Chinese leader will also travel to Washington, D.C., later in the week to meet with President Barack Obama.

Boeing has said the new factory in China would not lead to layoffs. But machinist union members said it could still cost them work, and they protested on Wednesday.