BEIRUT, Lebanon — Iran failed to resolve lingering questions about alleged nuclear weapons research and modestly expanded its ability to produce sensitive radioactive material that could potentially be used for a bomb, said a report issued Monday by the U.N.'s atomic watchdog for its board of directors.
Still, Iran is less than one-third of the way toward producing enough nuclear material for a single atomic weapon unless it drastically expands its program, nuclear experts have said.
The six-page report by the International Atomic Energy Agency, or IAEA, contains few of the words of praise for Iran's cooperation with nuclear inspectors included in previous assessments, a sign of the agency's growing frustration at what its officials have privately called Tehran's intransigence.
A senior U.N. official, who spoke to reporters on condition of anonymity, described the situation as gridlock and said Iran so far had not been forthcoming in replying to questions.
The report also contained a surprise reference to evidence of "foreign expertise" assisting in Iran's past nuclear efforts.
The senior U.N. official declined to disclose details about the nature of the help, but said that it came from outside the secret nuclear sales network of Pakistani scientist Abdul Qader Khan. The officials said the danger of freelance nuclear guns-for-hire was considered serious enough to pursue it with Iran.
The report will be taken up by the IAEA board of governors at a meeting in Vienna next week.
It may provide ammunition for Western and Israeli officials seeking to impose a fourth round of U.N. Security Council sanctions on Iran over its refusal to stop enriching uranium.
However, some analysts predict it will not be enough to overcome the reluctance of Russia and China, which wield veto power over the council, to impose harsh measures against Iran anytime soon.