IRAN said yesterday it was not clear when UN atomic inspectors would be allowed back into the country and said the decision to bar them reflected Tehran?s anger at an ?insulting? resolution on its nuclear activities.

?This was a response to the insulting tone of the resolution. We don?t allow them to talk to us in such a way,? Foreign Ministry spokesman Hamid Reza Asefi told a weekly news conference. ?When and how a new date is set, I do not know.?

US officials described the inspections move as ?very worrying?. But International Atomic Energy Agency (IAEA) chief Mohamed ElBaradei said he was confident Iran would reverse its decision to block IAEA inspectors from visiting the country.

Asefi said the move reflected a decision taken by Tehran ? which strongly rejects US accusations that it is pursuing nuclear arms ? regarding its cooperation with the UN body.

He said the resolution on the Islamic Republic adopted by the IAEA?s board of governors on Saturday at the agency?s Vienna headquarters ?did not take into account the realities?.

Iran feels the resolution focused too heavily on omissions and failures in Iran?s communications with the IAEA and failed to highlight its signature of a protocol in December allowing snap inspections of nuclear facilities and its decision temporarily to suspend uranium enrichment.

?The reality should be reflected (in the resolution). If not, the manner of our cooperation may change. Stopping the inspectors from visiting Iran should be evaluated in that framework,? Asefi said.

Cooperation may change

In the resolution, the IAEA board said it ?deplores? Iran?s omissions of key atomic technology from an October declaration, including undeclared research on advanced ?P2?centrifuges that can make bomb-grade uranium. It said the board of governors would decide in June how to respond to the omissions -- a clause that several diplomats said keeps the door open for a possible report to the UN Security Council and economic sanctions.

A senior US official, speaking to Reuters on condition of anonymity, said the postponed inspections were supposed to take place at the Natanz enrichment site, which Iran had hid from the IAEA until an exile opposition group reported it in August 2002.

?The real issue here is are the Iranians serious about giving up nuclear weapons or are they playing games,? he said. ?If we?re correct in our analysis that Iran continues to pursue nuclear weapons, then it follows...they have sites and activities that are not yet known to the IAEA.?

He added that there may even be undeclared sites inside the massive Natanz complex that the IAEA does not know about yet.

But Asefi insisted Iran was hiding nothing from inspectors and did not fear being referred to the UN Security Council.

?We?re not worried that our case will be sent to Security Council because, in the first place, we have had good and clear cooperation with the agency and, secondly, we have told them about everything and not hidden anything from them,? he said.