VIENNA (AP) — Iran is in the final stages of sanitizing a military site it is suspected of using for secret nuclear weapons-related experiments, two senior diplomats said Tuesday, as the U.N. atomic agency intensified efforts to gain access to the area before the alleged clean-up succeeds in erasing any traces of such work.

Iran, which insists its nuclear program is peaceful contrary to Western fears, has denied experts of the U.N.’s International Atomic Energy Agency permission to visit the Parchin site despite multiple requests from the agency this year. Tehran says a visit is possible only after extensive planning and a detailed outline of procedures — a caveat IAEA officials describe as a stalling tactic.