VIENNA, Austria — A report from the U.N nuclear watchdog agency on Thursday found Iran to be generally truthful about key aspects of its nuclear history, but it warned that its knowledge of Tehran's present atomic work was shrinking.

The International Atomic Energy Agency report, released to its 35 board members, also confirmed that Tehran continued to defy the U.N. Security Council by ignoring its repeated demands to freeze uranium enrichment, a potential pathway to nuclear arms.

The report was unlikely to satisfy the United States and its allies, who have said they will press for new Security Council sanctions unless Iran suspends enrichment and provides a full and detailed disclosure of past suspicious nuclear activities.

Reflecting that stance, Britain's Foreign Office said shortly after the report was issued that it would pursue further sanctions from the Security Council and the European Union.

"If Iran wants to restore trust in its program, it must come clean on all outstanding issues without delay," the statement said. It also said Tehran must restore broader and stronger inspection rights to IAEA teams and mothball its enrichment activities to avoid such penalties.

Much of the 10-page report made available to The Associated Press focused on the history of Iran's black-market procurements and past development of its enrichment technology — and the agency appeared to be giving Tehran a pass on that issue, repeatedly saying it concludes that "Iran's statements are consistent with ... information available to the agency."

A senior U.N. official said that language did not mean that the IAEA's investigation into past enrichment activities was "closed," even though a work plan between the agency and Tehran set November as the deadline for clearing up the issue.