“Sandy (Phan-Gillis’ nickname) is not a spy”, he said.

With Chinese President Xi Jinping making a state visit to the United States, a man in the southern USA city of Houston is using the occasion to call attention to the case of his wife who has been detained in China for the past six months on allegations of spying and stealing state secrets.

Sandy Phan-Gillis, from Texas, has been held by Chinese authorities for about six months, according to a statement from her family that was released online this week.

“Sandy is not a spy or a thief”, her husband Jeff Gillis said, according to the statement.

“The person you mentioned… is suspected of carrying out activities endangering national security, and is now being investigated by relevant departments”, he said.

It was not clear why the case had not been publicised until Monday, when the first announcements were posted to the site.

The New York Times reports that she has now been arrested, citing her husband and lawyer.

She has not been formally charged with any crime and was moved Sunday to a facility in Nanning.

Ms Phan Gillis consulted for USA and Chinese companies and was president of the Houston Shenzhen Sister City Organization.

There continues to be no official comment in the Chinese authorities with regards to the case.

Jeff Gillis said he hoped that the Xi’s visit would open opportunities for the USA administration to press for her release after months of secretive and fruitless efforts on his own.

The website describes Phan-Gillis as in “very poor health” and suffering from ailments including high blood pressure.

After eventually moving on without her, a message was sent from her phone saying “something to the effect of “I’m going to stay behind, to take care of personal matters”, Mr Gonzalez said.

“She is now well and healthy”, Hong said, also stressing that her “rights are being respected”.

The United States embassy in Beijing referred the BBC in Washington, that was shut during the period of enquiry and wouldn’t comment on the narrative.