The White House has contacted China's Foreign Ministry over the detention of an American businesswoman accused of spying, a spokesman said on Tuesday, in a case that blew up just as President Xi Jinping began a visit to the United States.

Sandy Phan-Gillis of Houston, Texas, has been held by Chinese authorities for about six months under suspicion of spying and stealing state secrets, according to a statement from her family released this week.

White House spokesman Josh Earnest told reporters it was "disconcerting" that many of the U.S. government's questions "have gone unanswered" by Chinese officials about the status of Phan-Gillis.