BERLIN (AP) — The United Nations' atomic watchdog agency said Wednesday its inspectors have been able to visit the second of two disputed sites where Iran is suspected of having stored or used undeclared nuclear material in the past.

Rafael Grossi, director general of the International Atomic Energy Agency, in late August secured an agreement with Iran to inspect the two sites in the country, thought to date from the early 2000s.

One site was inspected shortly afterward and the Vienna-based IAEA said the second site was visited this week by inspectors who took environmental samples.

Those will now be analyzed by labs that are part of the IAEA's network, including its own facility in Seibersdorf, Austria.

No results have been announced.

World powers had been calling for IAEA access to the sites since the agency in March identified them as places where Iran possibly stored or used undeclared nuclear material, or undertook nuclear-related activities without declaring them to international observers.

Iran had been permitting IAEA inspectors in to current nuclear sites agreed upon in the landmark 2015 nuclear deal with world powers, but had argued the other two sites dated from before the deal so there was no reason to grant access there.