The International Atomic Energy Agency (IAEA) on Wednesday adopted a resolution calling on Iran to co-operate with nuclear inspectors.
The Board of Governors of the Vienna-based agency on Wednesday passed the resolution asking Tehran to explain why traces of nuclear material were found in a number of facilities.
The text stated that clarifications from Iran are "essential and urgent," and demanded that IAEA inspectors be given the necessary access to official Iranian documents, information and sites.
Officials said 20 countries supported the resolution, while Russia and China voted against it and 12 countries abstained.
A statement formulated by Germany, France and the United Kingdom said IAEA Director General Rafael Grossi is currently "unable to provide this Board and the wider international community the assurance that Iran’s nuclear programme is exclusively peaceful."
The IAEA is closely involved in inspecting Iran's nuclear programme.
Tehran last year agreed to work with the agency in a "spirit of cooperation," but progress has stagnated, and the recent death of Iran's president Ebrahim Raisi and foreign minister Hossein Amirabdollahian in a helicopter crash led to the cancellation of planned technical talks.
While Iran's official nuclear strategy does not envisage the building of nuclear weapons, several recent statements by Iranian leaders have hinted at the country's ability to construct a nuclear arsenal. Grossi has repeatedly said that Tehran produces uranium at a purity level that is almost suitable for nuclear weapons.