On Tuesday, Democratic Sen. Ron Wyden of Oregon said the NSA has committed “more serious” violations of existing limits on spying than the government has disclosed. Speaking to MSNBC’s Andrea Mitchell, Wyden said his concerns came on top of a recent admission from National Intelligence Director James Clapper over violations of court orders.

Sen. Ron Wyden: “They did say last Friday that there had been violations of those court orders with respect to the bulk phone record collection, so that’s on the record. I’ll tell you those violations are more serious than they stated.”

Wyden has been unable to explain his concerns in detail because the surveillance operations are classified. On Friday, James Clapper sent Wyden a letter admitting “a number of compliance problems” with the bulk collection of U.S. phone data, but said there were “no findings of any intentional or bad-faith violations.” Clapper has previously apologized for falsely telling Wyden during a March hearing the NSA does “not wittingly” collect data on millions of Americans.