Iran has rejected the ultimatum by the United Nation's Security Council to suspend uranium enrichment before April 28.
"Iran's uranium enrichment activities are irrevocable," foreign ministry spokesman Hamid-Reza Assefi said at a press conference.
He denied press reports that Iran had promised the International Atomic Energy Agency (IAEA) a temporary suspension of the enrichment process.
Assefi said that Iranian diplomats were currently in Vienna to elaborate further on Iran's nuclear stance, but he voiced concern about the contents of the final report on Iran's nuclear activities to be presented by IAEA chief Mohamed ElBaradei.
"If the report is based on a correct technical evaluation, then there will be no grounds for any worry, but our concern has always been - and still is - the politicisation of the case," the spokesman said.
The UN Security Council is awaiting ElBaradei's report before taking action on Iran.
The Islamic state might face trade sanctions, but at least two of the council members, China and Russia, are reportedly against sanctions.
Assefi noted that Iran had so far only worked with P-1 centrifuges, but added that the use of P-2 centrifuges - which accelerate the enrichment process - would be in line with the Nuclear Non-Proliferation Treaty (NPT).
{{/usCountry}}Assefi noted that Iran had so far only worked with P-1 centrifuges, but added that the use of P-2 centrifuges - which accelerate the enrichment process - would be in line with the Nuclear Non-Proliferation Treaty (NPT).
{{/usCountry}}"Iran could, therefore, not be prohibited from using them," noted Assefi.
He reiterated that the Russian proposal to enrich converted Iranian uranium on Russian territory was still under consideration.
Assefi referred to the cancellation of the scheduled visit of the IAEA team to Iran and said: "Iran would welcome IAEA officials and inspectors whenever they want (to visit)."