Iranian Foreign Minister Ali Akbar Salehi has said he sees no more room for compromise in the battle over Iran's contested nuclear programme, in an interview published Sunday.
"I think there's no more point in making additional concessions," he told the German news weekly Der Spiegel.
"The nuclear question is just a pretext to weaken us by all means," he added.
Salehi rejected an International Atomic Energy Agency (IAEA) report released Tuesday citing "credible" evidence that Iran had worked towards nuclear weapons, saying the Vienna-based agency had given up its "earlier objectivity".
He said IAEA head Yukiya Amano was headed for hard times.
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"We will call him and the atomic energy authority to account for these conclusions," he warned.
Iranian officials characterised the IAEA report as "baseless" and hewing to intelligence provided by Israel and the United States.
Iran's parliament speaker Ali Larijani warned Sunday that Iran must review its cooperation with the UN nuclear watchdog due to the hostile nature of the report.
Germany, Europe's biggest exporter to Iran, plans to further limit bilateral trade, a government spokesman was quoted by Spiegel on Sunday as saying.
"Germany will actively support tougher sanctions against Iran," Steffen Seibert told the news weekly.
The European Union is preparing a new round of sanctions against Iran, but diplomats said the measures would likely not be finalised in time for a meeting of EU foreign ministers on Monday.