The report, to be delivered to the board of the Vienna-based International Atomic Energy Agency later Friday, will include the figure of 27 percent enrichment, the diplomat said, a potentially alarming development since it moves the purity of Iran’s uranium enrichment closer toward bomb-grade material even as a group of six world powers are negotiating with Tehran to shift its nuclear program in the opposite direction.
Whether the 27 percent figure represents a trace amount or a substantial quantity appears for the moment to be unknown publicly.
The disclosure, first reported by The Associated Press, came less than a day after Iran and the group of six world powers ended a round of difficult negotiations held in Baghdad on Iran’s disputed nuclear program with no substantive progress, although both sides agreed to meet again in Moscow next month.
The diplomat in Vienna, speaking on the condition of anonymity because of the issue’s sensitivity, cautioned that I.A.E.A. is investigating the reading and that the spike in purity could turn out to be accidental.
“There’s a decent chance that it’s an operator error,” the diplomat said.
Until now, the highest reported level of uranium enrichment for the Iranian program was 20 percent. The Nuclear Nonproliferation Treaty makes no restrictions on how pure a nation can make its enriched uranium, only that it cannot mix the civilian work with military applications.
In Iran’s case, the I.A.E.A. and Western powers have amassed evidence suggesting that Iran has investigated the making of nuclear arms, even as Tehran insists that all its atomic efforts are peaceful.
Most uranium fuel for reactors is enriched to around 4 percent purity. Iran began more than two years ago producing fuel enriched to 20 percent, saying it was for a research reactor in Tehran.
Bomb-grade fuel requires purity of 90 percent, which, in terms of production efforts, is a comparatively short leap from 20 percent enrichment.