The US Defense Department has designated Chinese-funded cultural centres on university campuses known as Confucius Institutes as a threat to US national security, Defense Secretary Pete Hegseth said.

Hegseth, in a video posted on social media on Friday, alleged that Confucius Institutes were operating under disguise at US universities and that the Pentagon had added them to its list of institutions that threaten US national security.

"It turns out that 80 new propaganda cells across 30 universities had popped up using different names and different charters, but with the same mission: to steal intellectual property and to infiltrate the minds of American students," Hegseth said.

Washington has long accused Confucius Institutes of being Chinese propaganda tools and has taken steps to crack down on them.

The Defense Department over the past two months has "systematically dismantled every single one of these organisations," Hegseth said.

US Congress restricted funding to universities that welcome Confucius Institutes, which are funded by Beijing to teach the Chinese language but are accused of presenting only the communist government's worldview.

The Chinese embassy in Washington did not immediately respond to a request for comment.