VIENNA (AP) — Iran’s president has promised to back a United Nations probe into suspicions that the country secretly worked on nuclear arms, the U.N.’s chief nuclear inspector said Sunday after talks in Tehran.

Yukiya Amano of the International Atomic Energy Agency described the meetings as “useful.” Still, it was unclear whether his agency would be able to make much progress by Aug. 25 — the deadline agreed on by the two sides to advance an IAEA investigation that has essentially been stalled for seven years.