With just five days to go before the expiry of a UN Security Council deadline for Iran to freeze uranium enrichment, Tehran shows no signs of backing down.
"The suspension of Iran's activities is media propaganda. Iran's research activities are irreversible," foreign ministry spokesman Hamid Reza Asefi told reporters.
The Security Council has given Tehran until Friday to suspend uranium enrichment, a process which makes reactor fuel but can be extended to make weapons.
Iran has refused to do so, despite growing talk of a possible US military strike, asserting that its nuclear drive is a legitimate bid to generate energy.
Mohamed ElBaradei, director of the International Atomic Energy Agency, is to report on Iran's compliance in a week and diplomats predict he will be less than complimentary about the Islamic regime.
"The fact that Westerners say it will be a negative report shows they are applying pressure," Mr Asefi said. "We are worried that Iran's dossier is being politicised.”
"We have to wait and see what Mr ElBaradei's report will be. He has not implied in previous reports that Iran has deviated from peaceful nuclear work," he said.
The Security Council called on March 29 for Iran to honour within 30 days IAEA resolutions for Tehran to halt enrichment and to cooperate with the agency's more than three-year investigation of its nuclear program.
Earlier this month Iran announced its scientists had successfully enriched uranium to make nuclear fuel, triggering global alarm and heightening the pressure on the Islamic republic.
In a new sign of defiance, hardline President Mahmoud Ahmadinejad has also vowed that the next step will be working on highly efficient P2 centrifuges, which can enrich far more effectively than the P1 technology currently used.
Mr Asefi denied that Iran has used the new technology but said "the Islamic republic has the right to use this machinery as a member of the (nuclear Non-Proliferation) Treaty and it cannot be deprived of it".
The United States is pushing for moves that could lead to economic and other sanctions if Tehran fails to comply but key Iranian trading partners Russia and China are resisting such measures.