Iran said last week it had begun enriching uranium to 20 percent of purity at the Fordo underground facility and was ready to bar the UN atomic agency’s inspectors from accessing its nuclear sites unless the United States scrapped sanctions in February.
"It is clear that we don’t have many months ahead of us. We have rather weeks," Grossi said during the Reuters Next virtual forum.
Grossi said Iran was making strides in stockpiling enriched uranium and would likely be able to produce 10 kilograms (22 pounds) of it per month at the Fordo plant.
The Iranian parliament passed a bill in November ordering uranium enrichment to be scaled up, in a bid to put pressure on the US after it quit the pact and reintroduced crippling economic sanctions on Tehran in 2018.