A date has been set for inspectors from the UN's International Atomic Energy Agency to visit a recently-revealed uraninium enrichment plant in Iran.
IAEA director Mohamed El Baradei said in Tehran they will go there on 25 October.
Iran disclosed the existence of the plant, built into a mountain near the city of Qom, on 21 September.
The BBC reports Tehran insists it has the right to develop nuclear energy for domestic usage.
However, the disclosure of the second facility has heightened fears among Western governments that it is trying to develop nuclear weapons.
Talks were held in Geneva last week between Iran and the five permanent members of the Security Council plus Germany. The meeting was the first since July 2008.
Iran agreed to co-operate "fully and immediately" on the second facility.