Senior UN investigators are in Iran for a new round of talks with government officials over allegations that Tehran may have carried out tests on triggers for atomic weapons, The Associated Press reports.

Iranian state TV said Wednesday, Feb 13, that talks with the International Atomic Energy Agency could be extended beyond the day, "if necessary."

The visit by the UN team, led by Herman Nackaerts, comes a day after Tehran raised prospects that the IAEA may be allowed to inspect Parchin, a military site where the agency suspects nuclear-related experiments were conducted.

Iran denies any such activities and insists Parchin is only a conventional military site.

The U.S. and its allies fear Iran is seeking to develop nuclear weapons. Tehran denies the charge, saying its nuclear program is only for peaceful purposes.