Yuance Chen, 38, and Liren Lai, 39, face charges of acting as agents of the Chinese government and a maximum sentence of 10 years in prison if convicted, the department said.

Chen, a resident of Happy Valley, Oregon, and Lai, who arrived in Houston, Texas, in April on a tourist visa, were arrested by the FBI on Friday, it said.

According to a criminal complaint, Chen and Lai carried out a number of intelligence activities in the United States on behalf of China's Ministry of State Security.

The activities included paying cash for national security information and seeking to recruit members of the US Navy as potential assets of the Ministry of State Security.

"This case underscores the Chinese government's sustained and aggressive effort to infiltrate our military and undermine our national security from within," Attorney General Pamela Bondi said in a statement.

According to the criminal complaint, Lai recruited Chen, a legal permanent resident of the United States, to work for the Ministry of State Security in 2021.

Asked about the case on Wednesday, China's foreign ministry said it "opposed the hyping up of so-called Chinese spies".

"We will also take necessary measures to safeguard the lawful rights and interests of Chinese citizens", foreign ministry spokeswoman Mao Ning said.