A former television news anchor and Chinese-born Australian citizen was faces national security charges for allegedly supplying Chinese state secrets to other countries.

Chinese police charged Cheng Lei on Monday and informed the Australian government. Cheng previously worked for state-owned broadcaster CGTN. She was formally arrested over the weekend after being detained for nearly six months. The charges are expected to further escalate the already elevated tensions between Australia and China.

Australian Foreign Minister Marise Payne said that Chinese authorities informed them that Cheng was being charged with endangering the country's national security by carrying out "criminal activities," including espionage.

Cheng was detained by Chinese authorities in mid-August. China has a provision that allows the detention of suspected criminals for as long as six months without filing charges. Australian embassy officials reportedly visited Cheng several times during her detention in accordance with Australia's consular agreement with China.

"[Australia] has raised its serious concerns about Ms. Cheng's detention regularly at senior levels, including about her welfare and conditions of detention. We expect basic standards of justice, procedural fairness, and humane treatment to be met, in accordance with international norms," Australian embassy officials said.

Cheng hosted several business-related television shows on CGTN. She had been working at the broadcasting network since 2012. Throughout her career, Cheng had built a relationship with some of China's most prominent businessmen, diplomats, and journalists.

Before she worked for CGTN, Cheng was a correspondent for CNBC focused on Asia and China. She graduated from the University of Queensland with a degree in commerce. She previously worked as an accountant at Cadbury Schweppes.

The charges filed against Cheng are the most serious allegations brought against a foreign journalist working in China.

The arrest is the latest development in the dispute between the two nations related to journalists and espionage. Last year, China pulled out four state media journalists from Australia after their homes were raided. Australia also pulled out several correspondents in China after authorities reportedly tried to detain them.

Chinese Foreign Ministry spokesman Zhao said that the attempt to detain the Australian journalists for questions was unrelated to the raids on the Chinese journalists in Australia.