Oklahoma Sen. Jim Inhofe, the top Republican on the Senate Armed Services Committee, says new revelations about the National Security Agency’s surveillance program suggest the Obama administration has “abused the authority granted to them by Congress” and that he will investigate the matter.

Inhofe’s statement shows a growing concern on Capitol Hill about the scope of the NSA’s intelligence gathering and adds to the calls for additional congressional oversight.

The NSA broke privacy rules or overstepped its legal authority thousands of times each year since Congress granted it broad new powers in 2008, according to an internal audit and other top-secret documents provided to The Washington Post, which first reported the story.

House Minority Leader Nancy Pelosi, D-Calif., on Friday called the revelations “extremely disturbing” and urged for additional oversight. But she has not called for a congressional investigation.