Sandy Phan-Gillis, from Houston, Texas, was arrested in China in March 2015. (AP photo)
An American businesswoman held in China since last year has been charged with spying on behalf of the US government, a case that has added to growing US-China tensions.
Sandy Phan-Gillis, a 56-year-old naturalized US citizen born in Vietnam and of Chinese descent, was arrested in China in March 2015.
Phan-Gillis, who was based in Houston, Texas, was detained during a visit to southern China as part of an American trade delegation.
"Based on our understanding, Phan-Gillis, because of her suspected crimes of espionage, has been charged according to law by the relevant Chinese department," Chinese Foreign Ministry spokeswoman Hua Chunying told reporters on Tuesday at a regular press briefing.
"China is a country ruled by law. The relevant Chinese department will handle the case strictly according to law," she said, without elaborating.
The US State Department has urged China to resolve the case "expeditiously."
In a letter transcribed by a US consular official in China, Phan-Gillis had said her detention was because of politics and not for any crime. “I am accused of being a spy for the US government. I have never been a spy.”
Her husband, Jeff Gillis, said Chinese investigators have asked her to confess to being a US spy from 1996-1998. “The charges are absolutely false,” Gillis said in a statement detailing the allegations against his wife, which hadn’t been disclosed previously.
The accusation comes amid heightened tension in US-China relations, including disagreements over territorial disputes in the South China Sea and the sentencing of a Chinese citizen in the US for hacking sensitive military information.
China’s territorial claims over the South China Sea overlap in parts with those of Taiwan, the Philippines, Vietnam, Malaysia and Brunei.
The United States has complained that Chinese planes and ships have performed "unsafe" maneuvers while shadowing American warships and aircraft in the South China Sea.
However, China has criticized the US military presence in the Asia Pacific and suspects Washington’s military drills with countries in the region are part of efforts to contain Beijing.
US President Barack Obama will travel to China on Saturday for a G20 summit in the city of Hangzhou.