Iran has confirmed that it has begun processing uranium to prepare it for enrichment - a process that can be used to make nuclear weapons.

But Iran's chief delegate to the International Atomic Energy Agency, Hossein Mousavian, told reporters in Vienna Wednesday the processing of a few tons of uranium is an experimental process, not an industrial production and that the IAEA is fully aware of it.

IAEA spokesperson, Melissa Fleming, said inspectors are visiting the Iranian facility to determine the extent of the activity.

Last month, the IAEA board of governors passed a resolution demanding that Iran freeze all activities connected with uranium enrichment. The board also threatened "further steps" if Tehran fails to comply.

The United States accuses Tehran of seeking to build nuclear weapons. Iran says the purpose of its nuclear program is only to produce electricity.