Iran is enriching uranium to 4.5% purity, above the 3.67% limit set by its deal with major powers, the UN nuclear watchdog policing the deal told member states in a closed-door meeting on Wednesday, diplomats familiar with the figures said.
The International Atomic Energy Agency had previously said on Monday only that Iran was over the 3.67% limit, its second breach of the 2015 deal in as many weeks, Reuters reported.
An Iranian spokesman said on Monday it had passed 4.5%, according to the semi-official news agency ISNA.
On July 1 the IAEA verified that Iran's stock of enriched uranium was 205 kg, more than the maximum 202.8 kg allowed under the agreement.
However, at Wednesday's meeting, IAEA officials revealed that Iran's stock of enriched uranium has now reached 213.5 kg. Both figures were verified on Tuesday, the four diplomats said.
Monday's enrichment level was verified using online enrichment monitors, which report in real time. They said the level reported on Wednesday, however, was the result of a sample analysis.
It was not immediately clear whether the samples tested were taken on Monday or Tuesday.
According to Reuters, the rise in the enrichment level is still far below the 20% Iran refined to before the nuclear accord, and the roughly 90% needed to make uranium weapons-grade.
Iran says it is responding to punishing economic sanctions the United States has imposed on Tehran since Washington pulled out of the nuclear deal a year ago.
