Iran's ambassador to Vienna-based international organizations, Kazem Gharibabadi, on Tuesday criticized a recent report by the International Atomic Energy Agency (IAEA) on Iran's nuclear activities as "political", the Xinhua news agency reports.

The report by IAEA Director General Rafael Grossi is "invalid" since it is not based on reliable sources and does not reflect all aspects of Iran's cooperation, Gharibabadi was quoted as saying.

Constructive interaction needs positive atmosphere and avoidance of prejudgment and unreal concerns, he said, adding that the IAEA's reports should avoid political agenda.

Last week, the IAEA released a report saying that Iran has failed to explain traces of uranium found at several undeclared sites.

"After many months, Iran has not provided the necessary explanation for the presence of the nuclear material particles at any of the three locations where the Agency has conducted complementary accesses (inspections)," the report said.

On Monday, Grossi said Iran has failed to answer questions about the discovery of uranium particles at former undeclared sites in the country and called on Tehran to provide information “without further delay.”

Grossi has been pushing Iran for answers on three sites dating back many years where inspections had revealed traces of uranium of man-made origin, suggesting they were once connected to Iran’s nuclear program.

While the IAEA has not identified the sites in question, one of them is believed to be the Turquzabad facility which was identified by Prime Minister Benjamin Netanyahu during his address before the UN General Assembly in 2018 as a "secret atomic warehouse."