Mr. Leahy disagreed with today's Intelligence Committee statement, which was issued by Mr. Boren and Senator William S. Cohen, the Maine Republican who is the committee's vice chairman. Mr. Leahy said he had announced last December that he planned to leave the committee after the 100th Congress was sworn in because he was taking over as chairman of the Senate Agriculture Committee.

''I had already said I would leave the committee early, and I moved it up and made it formal because I was so angry at myself,'' Mr. Leahy said. ''As soon as I saw the NBC story, I was the person who called Senator Boren and said, 'That has to be the report that was sitting on my desk.' ''

His term on the Intelligence Committee would not have expired until July, six months after the new Congress convened.

''Not that I blame anybody but myself,'' he said. ''Even though it was declassified, I was way too careless about it.'' White House Sought Publication

The report at issue was drafted by the staff of the Senate Intelligence Committee in the waning days of the Republicans' control of the Senate. The Intelligence Committee narrowly voted against releasing the document, even though the White House was pressing hard for its publication.