"Iran for its part is determined to pursue all legal areas of nuclear technology, including (uranium) enrichment exclusively for peaceful purposes," Kharazi said.
German Foreign Minister Joschka Fischer warned here Monday that resumption of enrichment activities by Iran "would lead to a collapse of the talks" with the European Union on getting Iran to give guarantees it is not making atom bombs.
Fischer said a breakdown in negotiations would also lead to a push by Europe and the United States, which charges that Iran is secretly developing nuclear weapons, to take Iran before the UN Security Council for possible international sanctions.
The United States on Tuesday renewed its call that Iran abandon its uranimum enrichment program, which makes fuel for nuclear power reactors but what can also be the explosive material for atom bombs.
"There is no reason for them to have an enrichment and reprocessing program," said State Department spokesman Richard Boucher.
The US envoy to the UN conference Stephen Rademaker had Monday called for "permanent cessation of Iran's enrichment and reprocessing efforts as well as dismantlement of equipment and facilities related to such activities."
But Iran, which Western states say is among the influences undermining the NPT treaty, got some support from Security Council member China on Tuesday.
Chinese delegation head Zhang Yan said China "favors resolving the Iranian nuclear issue within the framework of the IAEA," the Vienna-based International Atomic Energy Agency, which verifies NPT safeguards rather than in the Security Council.
Russian deputy foreign minister Sergei Kislyak sounded the same note when he said "current negotiations and consultations" should be enough to resolve the Iranian crisis.
China enunciated what is expected to be a key theme at the month-long NPT conference when Zhang said that "the relation between non-proliferation and the peaceful uses of nuclear energy should be put in correct perspective" so that respect is paid to "the rights of non-nuclear-weapons states to the peaceful uses of nuclear energy."
Kharazi said: "No one should be under the illusion that objective guarantees can theoretically or practically amount to cessation or even long-term suspension of legal activity" such as enrichment, which Iran claims is allowed for peaceful purposes under the NPT.
In Tehran, foreign ministry spokesman Hamid Reza Asefi said Tuesday that Iran would resume some nuclear activities suspended as part of a deal with the European Union, despite the threat of international sanctions.
Iran agreed in November last year to suspend its fuel cycle work in order to begin talks with EU negotiators Britain, France and Germany.
Kharazi also took clear aim at US comments made Monday when he said: "It is unacceptable that some tend to limit the access to peaceful nuclear technology to an exclusive club of technologically advanced states under the pretext of non-proliferation."
Rademaker targeted Iran on Monday, saying that, in line with the NPT, states not in compliance with nuclear safeguards should not get assistance in developing peaceful atomic technology.
The IAEA has however so far only judged Iran in breach of certain safeguards but not in a formal state of non-compliance.
Kharazi blasted nuclear-weapons states for not disarming as required by the NPT in what was also a clear dig at the United States.
"Some nuclear-weapons states are developing new and more easy-to-use nuclear weapons," Kharazi said, referring to mini-nukes, the so-called bunker busters which Washington is thinking of making.
Both China and South Africa called Tuesday for non-nuclear-weapons states to get legal guarantees that nuclear states will not attack them.
South African foreign ministry deputy director general Abdul Samad Minty said "non-nuclear-weapon states have the right to be provided with internationally legally binding security assurances under the NPT that would protect them against the use of threat of use of nuclear weapons."