A Chinese national working for Bloomberg News bureau in Beijing has been detained by Chinese authorities on suspicion he poses a risk to national security, the news agency reported on Friday.

Bloomberg disclosed that Haze Fan was last seen being taken by plainclothes security agents from her apartment building in Beijing at around noon Monday, moments after her last communication with her editors.

The U.S. financial news agency contacted the Chinese authorities and their consulate in Washington, DC, in a bid to know her whereabouts after she disappeared. It said Bloomberg LP, its mother company, was notified that Fan was being taken into custody.

China's Foreign Ministry confirmed that the Beijing State Security Bureau had initiated actions against Fan, who it claims is suspected of taking part in criminal activities that imperil the country's security.

Authorities said the situation is currently under probe, and Fan's legitimate rights are fully protected. The BSSB could not immediately be reached for a statement.

"We're very concerned for her, and have been actively communicating with Chinese authorities to better understand the situation," the Associated Press quoted an unnamed Bloomberg spokesperson as saying in its report.

John Micklethwait, Bloomberg editor-in-chief, and other senior editors told China-headquartered personnel that Chinese authorities had said Fan hadn't been detained in connection to her work, reports say.

The Chinese government has a vague definition of "endangering national security." The charge can result in lengthy detention with little recourse to legal assistance.

Washington has labeled Chinese media as government entities, and in May, the Trump administration hardened its policies for visas for Chinese journalists.

Fan, who covers Chinese business news topics for Bloomberg, started working for the news company in 2017.

She previously worked for Thomson Reuters, CNBC, CBS News, and Al Jazeera. Based on her LinkedIn profile, she completed a master's in international journalism at the University of Leeds in England in 2009.

Fan's detention comes amid growing frictions between western media groups and Beijing, as well as between the White House and China's state-run news organization.

China expelled reporters from The New York Times, The Wall Street Journal, and The Washington Post earlier this year, in the wake of complaints about content and moves by the U.S. government that revoked their press credentials as relations with Washington have soured.

The Beijing-based Foreign Correspondents' Club of China said it was very concerning to hear the news of Fan's detention and that that it was seeking to clarify why she had been detained.