China has launched an investigation against a woman from Texas who was arrested on charge of spying, her husband said in a public statement ahead of President Xi Jinping's US visit.

For last six months, Sandy Phan-Gillis has been held by Chinese authorities on charges of spying and stealing state secrets.

According to the family of the alleged spy, the US State Department has said that it was aware of her detention.

A Reuters report, quoting Chinese foreign ministry spokesman Hong Lei, said that Phan-Gillis was suspected of "endangering China's national security" and is being investigated by "relevant Chinese authorities".

It is the first time that China has publicly acknowledged that it was holding the US citizen captive for the last six months, The Wall Street Journal observed.

Jeff Gillis told Voice of America that his wife Sandy Phan-Gillis--an American citizen of Chinese descent--was arrested on 19 March in Guangzhou while on a business trip along with Houston officials and Chinese-American businessmen.

After keeping the case a low profile matter for months, Gillis said he lost hope seeing the lukewarm reaction from the US authorities. He said that he saw Xi's trip to the United States as an opportunity to get the public support to seek the release of his wife.