U.S. President Donald Trump's administration has asked the Environmental Protection Agency to temporarily halt all contracts, grants and interagency agreements pending a review, according to sources.

The White House sent a letter to the EPA's Office of Administration and Resources Management ordering the freeze on Monday, an EPA staffer told Reuters. "Basically no money moving anywhere until they can take a look," the staffer said, asking not to be named.

It was not immediately clear if the move would have any direct impact on automotive-related regulatory activities or initiatives.

The EPA awards billions of dollars worth of grants and contracts every year to support programs around environmental testing, cleanups and research. It also was unclear if the freeze would impact existing contracts, grants and agreements or just future ones.

Myron Ebell, who headed Trump's EPA transition team until his inauguration last week, said he believed the move was related to Trump's executive order on Monday temporarily halting all government hiring outside the military.

"A freeze at EPA on some other things like grants and contracts appears to have happened," Ebell told Reuters in an email Tuesday morning.