Islamic republic hits out after nuclear watchdog expressed 'serious concerns' over weapons studies.
Iran accused the UN nuclear watchdog on Sunday of giving in to Western pressure in its latest report on the Iranian nuclear drive which struck a tougher tone.
"We were expecting more than this from the agency," Foreign Ministry spokesman Mohammad Ali Hosseini told reporters.
"If it was not for the pressure from one or two countries, the agency could have made a better report which would not have given any opportunity for some countries who are seeking pretexts to put pressure on us."
In its report, the International Atomic Energy Agency (IAEA) expressed "serious concern" that Iran was hiding information about alleged studies into making nuclear warheads as well as defying UN demands to suspend uranium enrichment.
Hosseini's remarks underline Iran's growing frustration with the IAEA after Western countries seized on the report to repeat their concerns about the contested nuclear programme.
The new speaker of parliament Ali Larijani, a former nuclear negotiator, has condemned the agency's attitude as "regrettable" and warned that Tehran will consider revising its cooperation should this continue.
Hosseini also protested the IAEA was "not acting on its commitments" by continuing to investigate a document which shows how to machine uranium metal into two hemispheres of the kind used in nuclear warheads.
Iran in November handed over the document to the agency, which had been demanding it for two years.
He complained the agency previously said this case was closed: "One negative point in the [IAEA] report is to leave open the metal uranium document... Thus, we believe that the agency has not acted based on its commitments."
In the report, the IAEA says that "Iran needs to... provide more information on the circumstances of the acquisition of the uranium metal document".
According to diplomats, IAEA Deputy Director-General Olli Heinonen described the document as "alarming" at a closed door meeting.
"The agency should not permit any pretext from certain countries to affect the relations between the agency and this country," Hosseini added.
Observers said the report marked a tougher line from the IAEA, which has spent four years investigating the Iranian nuclear drive but has never drawn a conclusion over its goals.
The US and its European allies fear Iran wants to use the sensitive process of uranium enrichment to make an atomic weapon. Tehran insists its drive is entirely peaceful.For all the latest energy and oil news from the UAE and Gulf countries, follow us on Twitter and Linkedin, like us on Facebook and subscribe to our YouTube page, which is updated daily.