WASHINGTON — CIA Director John Brennan on Thursday acknowledged the use of “abhorrent” tactics by the spy agency — but he said harsh interrogations provided “useful intelligence,” a day after the release of a blistering Senate report on torture after 9/11.

Speaking in an unusual press conference at CIA headquarters, Brennan said some of the techniques were “abhorrent and should be repudiated by all” involved. But Brennan insisted that CIA-run interrogations produced useful information that “helped the United States thwart attack plans, capture terrorists and saved lives.”

Post-9/11, he said: “We feared more blows from an enemy we couldn’t see and an evil we couldn’t fathom.”

He called it “unknowable” if “enhanced interrogation techniques” led to useful intelligence.

Sen. Dianne Feinstein (D-Calif.) tweeted: “Brennan: ‘unknowable’ if we could have gotten the intel other ways. Study shows it IS knowable: CIA had info before torture.”