US federal prosecutors have accused two Chinese nationals of smuggling a dangerous biological pathogen that had the potential to be used as an agricultural terrorism weapon into the United States for research.

The US Department of Justice on Tuesday identified the pathogen as Fusarium graminearum, a fungus it said was classified in scientific literature as a potential agroterrorism weapon. In a statement, it said that the fungus causes “head blight” in some crops and is responsible for billions of dollars in economic losses globally each year.

According to an FBI criminal complaint, Zunyong Liu, 34, a researcher currently in China, brought the fungus into the US while visiting his girlfriend, Yunqing Jian, 33, in July 2024.

He admitted to smuggling in the fungus so he could conduct research on it at a University of Michigan laboratory where his girlfriend worked, according to the complaint.

The university did not immediately respond to a request for comment.

According to the complaint, an examination of electronic communications between the two indicated that they discussed shipping biological materials and research being done in the laboratory prior to Zunyong’s arrival.

Yunqing and Zunyong were accused in the complaint of conspiracy, smuggling goods into the US, false statements and visa fraud.

Cheyvoryea Gibson, special agent in charge of the FBI Detroit Field Office, said the pair’s actions “posed an imminent threat to public safety”.

Yunqing was expected to appear in court in Detroit, Michigan, on Tuesday. A judge appointed a public defender, who could not be immediately reached for comment, to represent her.