The United States plans to broaden oversight of foreigners' real estate transactions on properties close to military installations, the Treasury Department said Monday, as concerns involving Chinese land purchases grow.

"President (Joe) Biden and I remain committed to using our strong investment screening tool to defend America's national security, including actions that protect military installations from external threats," Treasury Secretary Janet Yellen said in a statement.

Under a proposed rule, more than 50 facilities will be added to a list of sites where surrounding property transactions may be reviewed by the Committee on Foreign Investment in the United States (CFIUS) -- taking the total figure to 227.

CFIUS's jurisdiction covers land purchases as well.

The concern is that a foreigner's purchase or lease of certain properties could allow them to collect intelligence or "expose national security activities" to foreign surveillance risks, the Treasury noted.

Among the proposed sites to be added are Camp Grayling in Michigan -- some 100 miles from where Chinese electric vehicle battery-maker Gotion plans to build a facility.

Republican congressman John Moolenaar of Michigan has pushed back on Gotion's plans, raising security concerns.

A senior Treasury official said CFIUS's jurisdiction was "country-agnostic" and did not specify if the latest rule was aimed at quelling concerns directed at specific countries like China or Russia.

In May, US authorities announced that a Chinese-owned crypto firm was barred from using land near a strategic US nuclear missile base over national security concerns.

MineOne Partners Limited was ordered to divest from land it bought in 2022, which sat less than a mile from Wyoming's Francis E. Warren Air Force Base -- home to Minuteman III intercontinental ballistic missiles.

CFIUS had also raised concerns about the installation of "specialized" crypto mining equipment on the land which is "potentially capable of facilitating surveillance and espionage activities."