Ahmadinejad said last month that Iranian scientists were putting 6,000 new uranium enriching centrifuges into place, about twice the existing number, and testing a new type that works five times faster.

But the diplomat who provided details on the report said it will say the rate of expansion has been much below that touted by Ahmadinejad.

He and other diplomats close to the IAEA previously said Iran has exaggerated its progress and is having problems operating the 3,000 centrifuges already in place.

Additionally, the diplomat speculated Tuesday that Iran might be holding back on a quick build-up of enrichment capabilities hoping it will be easier to come to terms with the U.S. administration that will succeed President Bush, known for his hard-line Iran policies.

The commonly accepted figure for a nuclear enrichment program can be used as a platform for a full industrial-scale program that could churn out enough enriched material for dozens of nuclear warheads over time.